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THE CHEMISTRY 


AND 


TECHNOLOGY OF PAINTS 


BY 


MAXIMILIAN TOCH 
Disc ch. CS-i-RiP Ss. CHE: 


Vice President, Toch Brothers, Inc. 
Author of ‘‘Materials for Permanent Painting”’ 
“How to Paint Permanent Pictures,’ etc. 
Formerly Professor Industrial Chemistry, Cooper Union, New York 
Honorary Professor Industrial Chemistry, Pekin, China 


THIRD EDITION, REVISED AND ENLARGED 





NEW YORK 
D. VAN NOSTRAND COMPANY 


EIGHT WARREN STREET 


1925 


COPYRIGHT, 1007, 19010.1702,5 36 
D. VAN NOSTRAND COMPANY 





All rights reserved, including that of translation 
into the Scandinavian and other foreign languages 


THE*PLIMPTON:PRESS 
NORWOOD:MASS:U°:S°A 


THE GETTY CENTER 
LIBRARY 


PREFACE TO FIRST EDITION 


Tue difficulty which I encountered in writing this 
book was not how much to write but how much to omit, 
for I found on compiling my notes that I could very 
easily have made two volumes, each larger than the 
present one, and still would not have covered the ground 
thoroughly. It is for this reason that I have omitted 
many of the pigments which are rarely used, and have 
paid no attention whatever to the pigments which have 
gone out of use. 

I have not considered it desirable to use any space in 
this book with extended repetition of matter that can be 
found in other books of reference, for I have so much 
matter which is the result of original research that very 
few references are cited. 

This being the first book ever written on the subject 
of mixed paints, I am cognizant of the fact that there 
are many matters in it which I shall have to alter in 
future editions, and many subjects upon which I shall 
have to enlarge It must be borne in mind that mixed 
paint is demanded by a progressive civilization and that 
there are no two manufacturers who make identically the 
same mixtures. As time changes, the progressive manu- 
facturer alters his formulas, and an indication of this is 
that the original mixed paints were mostly emulsions 
and soap solutions, whereas today the tendency is toward 
purity and improvement, and one manufacturer tries to 
outdo the other in making a paint that will last, the 
ideal paint, however, being never reached. 


lil 


iv PREFACE TO FIRST EDITION 


This volume is intended for the student in chemistry 
who desires to familiarize himself with paint, or the 
engineer who desires a better knowledge of the subject, 
or for the paint manufacturer and paint chemist as a 
work of reference. It is not intended for those who have 
no previous knowledge or training in the subject. 

Some of the chapters in this book are taken from my 
lectures delivered at various universities, and others are 
extracts from lectures delivered before scientific bodies. 
One of the objects which I have had in view during the 
entire time I have been writing this book is to familiarize 
the student in chemistry, or the post-graduate, with the 
science and technology of modern paints, so that in a 
very short time the chemist unfamiliar with the subject 
may obtain sufficient knowledge to make a reasonable 
examination of paint. 

The chapter on linseed oil illustrates this, and my 
researches and theories on the difference between raw 
and boiled linseed oil are here published for the first time. 
From the formulas and disquisition on the subject it 
can be easily seen that if raw linseed oil be taken as a 
standard nearly all comparisons fail if boiled linseed oil 
is under examination. 


320 Firth AVENUE 
NEw YORK, 1907 


Pee aCe TO, SECOND EDITION 


SINCE the first edition of this book was published the 
efforts of a large number of technical men working in this 
field have resulted in very important advances both in the 
production of new pigments, oils and special paints and in 
the scientific elucidation of many obscure phenomena in 
paint technology. Improvements have also been made in 
the method of manufacture as well as in the quality of 
many of the older pigments. Advances have also been 
made in the discovery and utilization of a number of oils 
which have not heretofore found extended use in the paint 
trade. 

These important advances have necessitated rewriting 
most of the book and the addition of new matter to the ex- 
tent of doubling its size. Some of the important additions 
which may be worthy of mention are, standard specifica- 
tions for pigments and oils; new special paints and driers; 
the theory of corrosion of iron and steel and its prevention 
as well as the action of fungi on paints; the important sub- 
ject of the hygiene of workmen; detailed methods of analy- 
sis of paints and paint materials as well as tables of 
constants of such materials. | 

Undoubtedly the chemical manufacturer and the chemical 
student who intends to become proficient in paint chemistry 
will find it essential to read a great deal of the past as well 
as the current technical literature of the subject, but it is 
the hope of the author that this book will give the student 
a comprehensive survey of the progress already made and 
furnish a foundation for further improvement. 


MAXIMILIAN TOCH 
320 FirtH AVENUE 
New York 


July, 1916 v 


PREFACE TQ THIRD EDITION 


SO many investigations have been made since 1917, 
and so many new materials have been added to the list of 
pigments and oils, that it has become necessary to rewrite 
the second edition of ‘*The Chemistry and Technology of 
Paints” and bring it up to date. 

Our viewpoint on China Wood Oil has been largely 
changed, due primarily to investigations of the growth of 
the tung oil tree and the collection and expression of the 
seeds, and for the further reason, that the transplantation 
of the tung oil tree on a large scale in the United States 
has given us an oil which differs materially from that which 
we have considered standard China Wood Oil. 

Perilla Oil although not yet used in very large quantities 
will probably become an important factor in the paint and 
varnish industry. 


110 HAST 42ND ST. 
New YorkK CITY 
September, 1925 
MAXIMILIAN TOCH 


I acknowledge with thanks the valuable assistance which I re- 
ceived from my associates, Dr. T. T. Ling, Dr. V. P. Krauss and 
Mr. Ralph T. Mayer. 

I am greatly indebted to my personal assistant, Dr. T. T. Ling, 
Mr. William M. Taylor of the Chemical Division of the Bureau of 
Foreign and Domestic Commerce, for his excellent article on China 
Wood Oil, No. 125, Julean D. Arnold, Commercial Attaché, Peking, 
and Consul General Heinzelmann at Hankow. 

I am indebted to Mess. L. C. Gillespie & Sons for three of 
the illustrations. 


CONTENTS 


PREFACE TO First EDITION 
PREFACE TO SECOND EDITION. 


INTRODUCTION . . 


CHAPTER 1 


THE MANUFACTURE OF MIXED PAINTS 


CHAPTER II 
THE WHITE PIGMENTS. 


White Lead. — Sulphate of seh Becca White eae — 
Ozark White. — Zinc Oxid. — Zinox. — Lithopone. — Titanium 
White. — Antimony Oxid. 


CHAPTER IIT 
THE Oxips oF LEAD 


Litharge. — Red Lead. — Blue eae 


CHAPTER IV 


THE INORGANIC RED PIGMENTS. 
Venetian Reds. — Indian Red. 


CHAPTER V 
THE YELLOW PIGMENTS 


American Yellow Ochre. — French Yellow unre oe Rae cae 
— Chrome Yellow. — Chromate of Zinc. — Yellow Iron Oxids. 
— Cadmium Yellow. — Antimony Sulphide. — Arsenic Sulphide. 


CHAPTER SSVI 
THE BRown PIGMENTS 


American Burnt Sienna. — Italian ee eare. — Raw and Burnt 
Umber. — Burnt Ochre. — Prince’s Metallic or Princess Mineral 
Brown. — Vandyke Brown. 


CHAPDER VII 
THE BLUE PIGMENTS . 


Ultramarine Blue, — Artificial epi Blue. — Pan Blue. 


vil 


ill 


23 


52 


62 


67 


75 


82 


vill CONTENTS 


CHAPTER VIII 
THE GREEN PIGMENTS 
Chrome Green. — Ghisucin Oxid. Bee l Chrome Oxid. — 
Verte Antique (Copper Green). 


CHAPTER IX 
THE BLAack PIGMENTS 


Lampblack.— Carbon Black.— BG raniitee es Charepall 7 Vi ine > Blade 
— Coal.— Ivory Black.— Drop Black.— Black Toner. — 
Benzol Black. — Acetylene Black. — Mineral Black. 


CHAPTER X 


THE INERT FILLERS AND EXTENDERS 


Barytes. — Artificial Barium Sulphate. — Bare Catone Sy 
Silica. — Infusorial Earth. — Kieselguhr. — Fuller’s Earth. — 
Clay. — Asbestine. — Asbestos. — Calcium Carbonate. — White 
Mineral Primer. — Marble Dust. — Spanish White. — Artificial 
Calcium Carbonate. — Gypsum. 


CHAPTER XI 
LAKES AND TONERS . ‘ 
Red Lakes. — Para one See pate Rac terhT >: or 
Alizarin Lake. — Other Lakes. — Oil Soluble Colors. 


CHAPTER XII 
MIxeEp PAINTs . 


Anti-fouling and Ship’ S Botton Points <= ~ Concteea or Pevctiaes 
Cement Paints. — Paint Containing Portland Cement. — Damp- 
Resisting Paints. — Enamel Paints. — Flat Wall Paints. — Floor 
Paints. — Shingle Stain and Shingle Paint. 


CHAPTER’ Xitil 
LINSEED OIL . 


Linseed Oil. Pee anette ARBOR Socios for Testing g 
Materials for Linseed Oil. — U. S. Navy Department Specifica- 
tions for Linseed Oil. — Stand Oil. — Japanner’s Prussian Brown 
Oil. — Perilla Oil. 

CHAPTER XIV 
Cu1nA Woop OIL é 

Production of Wood Oil. - — Rennes — Se ran — Heat 
Tests. — Quality Tests. — American Production. — Deodoriza- 
tion. — Lumbang Oil. — Stillingia Oil. 


CHAPTER XV 
SovA BEAN OIL. 


go 


95 


108 


140 


146 


164 


IQI 


225 


CONTENTS 


CHAPTER XVI 
FisH OIL 


CHAPTER XVII 
MISCELLANEOUS OILS. 


Herring Oil;— Corn Oil. 


CHAPTER XVIII 
TURPENTINE . 


eatrpenune’ <= Wood Turcenting. a Seeehn Srecneatione een 
can Society for Testing Materials for Turpentine. — U. S. Navy 
Department Specifications for Turpentine. 


CHAPTER XIX 
Pine OW .. 


CHAPTER XX 
BENZINE 


CHAPTER XXI 


~ 


‘TURPENTINE SUBSTITUTES . 
Benzo1. — Toluol. — Xylol. — Solvent Napntha. 


CHAPTER XXII 
COBALT DRIERS 


CHAPTER XXIII 


COMBINING MEDIUMS AND WATER 


Combining Mediums. — Water in the Cseitiah of Mixed Pune 


— Emulsifiers. — Emulsions. 


CHAP LER XXIV 
FINE GRINDING 


CHAPTER XXV 


THE INFLUENCE OF SUNLIGHT ON. PAINTS AND VARNISHES . 


CHAPTER XXVI 


PAINT VEHICLES AS PROTECTIVE AGENTS AGAINST CORROSION 


CHAPTER XXVII 


THE ELECTROLYTIC CORROSION OF STRUCTURAL STEEL. 


CHAPTER XXVIII 
PAINTERS’ HYGIENE 


1X 


243 


250 


268 


273 


277 


292 


204 


301 


BTT 


319 


xX CONTENTS 


CHAPTER XXIX 


THE GROWTH OF FUNGI'ON PAINT . 


CHAPTER XXX 


PHYSICAL EXAMINATION AND TESTING OF PIGMENTS 


CHAPTER XXXI 


ANALYSIS OF PAINT MATERIALS . 


White Lead. — Basic Lead quiphates a Zinc Lee S27 Oxid. 
— Lithopone. — Red Lead and Orange Mineral. — Iron Oxids. 
— Umbers and Siennas. — Mercury Vermilion. — Chrome Yel- 
lows and Oranges. — Chrome Greens. — Prussian Blue. — 
Ultramarine. — Black Pigments. — Graphite. — Blanc Fixe. — 
Whiting. — Gypsum or Calcium Sulphate. — Silica. — Asbes- 
tine. — Clay. — Barytes. — Barium Carbonate. — Mixed White 
Paints. — White Pigments. — Paints. — Rosin. — Rosin Oils. 
—= Oils tet Lc: 


APPENDIX 


BOILED OILS — CHARACTERISTICS. 
REFRACTOMETRY . 


CONVERSION OF FRENCH sale. INTO oe eon AND 
MEASURE 


METRIC SYSTEM OF WEIGHTS AND Meee 

SPECIFIC GRAVITY OF VARIOUS MATERIALS 

SPECIFIC GRAVITY OF THE ELEMENTS . . Bory 
PouNDS OF OIL REQUIRED FOR GRINDING I00 Poem OF ee ce 
_ PASTE FROM VARIOUS PIGMENTS 

SPECIFIC GRAVITY OF VARIOUS WooDs 

THERMOMETER CONVERSION TABLES 


BIBLIOGRAPHY . 


INDEX 


322 


326 


330 


388 
389 


394 
395 
396 
400 


400 
4OI 
402 


403 


407 


THE CHEMISTRY 


TECHNOLOGY OF PAINTS 
INTRODUCTION 


THE manufacture of mixed paints is_ essentially 
American, having been accredited to some enterprising 
New Englanders who observed that when a linseed oil 
paint was mixed with a solution of silicate of soda (water 
glass) an emulsion was formed, and the paint so made 
showed very little tendency to settle or harden in the 
package. Several lay claim to this discovery. The 
first mixed paint was marketed in small packages for 
home consumption and appeared about 1865. 

The addition of silicate of soda is still practised by a 
few manufacturers, but the tendency is to eliminate it 
as far as possible and to minimize as much as possible 
the use of an alkaline watery solution to keep the paint 
in suspension. The general use of zinc oxid has had 
much to do with the progress of mixed paint, for it is 
well known that corroded white lead and linseed oil 
settle quickly in the package, while zinc oxid keeps the 
heavier lead longer in suspension. Where only heavy 
materials are used, manufacturers are inclined to add 
up to 4 per cent of water. Under another chapter on 
“Water in the Composition of Mixed Paints,” page 286, 
this subject will be fully discussed. 

To the pigments are added many materials possessing 
but little body, hiding or covering property, which are 


I 


2 INTRODUCTION 


known as inert fillers, and some of these, particularly 
the silicates of alumina and the silicates of magnesia, 
the various calcium carbonates, and silica itself, are used 
to counterbalance the heavy weight or the specific gravity 
of the metallic pigments; and whereas these inert fillers 
were formerly regarded as adulterants and cheapening 
agents, they are now looked upon as necessities, and the 
consensus of opinion among practical and many scientific 
investigators 1s that a compound paint composed of lead, 
zinc, and a tinting pigment, to which an inert material 
has been added, is far more durable than paint made of 
an undiluted pigment. The consuming public and the 
painter himself have not been sufficiently educated as yet 
to understand the merits of these diluents, and the paint 
manufacturer has been reticent in his statements regard- 
ing the use of various fillers. 

These facts account to a large degree for the opposi- 
tion to the use of such materials. When it is taken 
into consideration that within forty years the sale of 
mixed paints in the United States has grown to almost 
sixty million gallons per year (and the outlook is for a 
larger increase in the use of mixed paints), it is obvious 
that the demand is healthy, even though the manufacture 
of mixed paints has been directed or based largely upon 
empirical formulas. 

One of the railroads of the United States buys at this 
writing upward of one million dollars’ worth of paint 
material per year, a large share of this being mixed paints, 
or paint ready for the brush. Nearly all of the large 
manufacturing industries which use large quantities of 
paint are gradually altering their methods, so that their 
paint comes to them ready for application. In no case, 
to the best knowledge of the author, does a single one 
of these industries prescribe a single pigment with linseed 


INTRODUCTION 3 


oil for general purposes, for it has been shown that a 
mixture of several pigments and a filler is superior from 
the standpoint of lasting quality and ease of application 
to a mixture of a single strong pigment and the vehicle. 

The structural iron industry, which has reached an 
enormous development in the United States, uses paints 
ready mixed with the one exception of red lead, which, in 
the old prescription of thirty-three pounds of red lead to 
one gallon of oil, cannot be prepared ready for the brush, 
for reasons which will appear in the proper chapter. 

The manufacture of agricultural implements, wagons, 
and wire screens can be cited as industries in which manu- 
facturers have within a very few years adopted the use 
of ready-mixed paints for their products. These paints 
are not brushed on, but are so scientifically made, and 
the relation between a vehicle and a pigment is so 
carefully observed, that large pieces of their products can 
be dipped into troughs and the paint allowed to drain. 
The surface is more evenly coated and the work done in 
far less time than would be required were it applied 
by means of the brush, as in former years. 

In view of all these facts, the prejudice on the part 
ot the general public and the trepidation of the manu- 
facturer are to blame for the unheralded knowledge of 
‘ the constituents of mixed paints. There are many cases 
where materials which were once despised are regarded 
now as essential to the life and working quality of paint, 
and the attitude of the paint manufacturer must in 
the future be a frank and open admission of the com- 
position of his materials. If a paint is composed of a 
mixture of white lead, zinc oxid, and barytes, and it has 
been proved that a mixture of these three will outlast 
a mixture of either of the other two, there is no reason 
why a manufacturer of mixed paints shall not so state. 


4+ INTRODUCTION 


New materials have come into use which have taken 
the place in a large degree for many purposes of the 
time-honored and useful white lead, and many mixed 
paint manufacturers have already begun to educate the 
public to the superiority of one material over another. 
It stands to reason, however, that the manufacturer of 
a raw material which has been in use for a very long 
time is going to refute as much as possible the statement 
made with regard to newer materials, and these dis- 
cussions tend to do good rather than harm. 

In the case of one of the large railroads, the speci- 
fications for a certain paint demand the use of over 70 
per cent of inert filler, and if these inert fillers had no 
merit no railroad or large corporation would permit their 
use. These large corporations support chemical labora- 
tories and employ the best talent which they can engage. 
They continually experiment, and in their specifications 
the results of their experiments are obvious, and there- 
fore if a large corporation can state publicly not only 
what the composition of these paints shall be, but con- 
clude that such compositions are based upon the results 
of scientific investigation, the paint manufacturer can 
do likewise and stand back of his products, provided they 
be mixtures of various materials which time, science, 
and investigation have proved to be superior. 

Unfortunately, however, there are some manufactur- 
ers who have ‘‘hidden behind a play of words” and per- 
mit chicanery and finesse to enter into the description 
of their products; but fortunately some of them have 
seen the errors of their way, and already there is a ten- 
dency toward openness and candor with regard to their 
wares. There was a time, and it still exists in a measure, 
when substitutes for white lead were very largely sold, 
and misleading labels appeared on the packages; for 


INTRODUCTION 5 


instance, a man would make a mixture of 80 per cent 
barytes and 20 per cent white lead, and would print 
on the label—‘‘The lead in this package is guaranteed 
absolutely pure,” followed by a commendation and 
guarantee that certain sums of money would be paid if 
the lead were not found to be pure. This, of course, is 
a moral fraud and an unfortunate play on the ambiguity 
of the language, and many of the manufacturers, in view 
of such unfortunate misstatements, are altering the 
names of their paste products, or lead _ substitutes, 
omitting the word “lead” entirely. 

Another unfortunate mistake is made when a manu- 
facturer makes a mixed paint and states on the label, 
“This paint is composed of pure lead, pure zinc, pure 
linseed oil, pure drier, and nothing else.”’ The analyses 
of the paint have proved that in addition to the “pure” 
products mentioned three gallons of water were added 
to every hundred gallons of paint in order to keep the 
paint in suspension, and that it had not been strained 
and therefore contained a large amount of dirt and for- 
eign matter. Ethics would clearly indicate that no 
manufacturer has a moral right to label his paint as 
being entirely pure and composed of four materials, 
when as a matter of fact an excessive quantity of water 
was added which destroyed in a large degree the value 
of the other materials. In another chapter the question 
of the percentage of water which may be contained in 
any paint will be thoroughly discussed. Three per cent 
is entirely excessive in an exterior linseed oil paint, and 
a manufacturer has no right, either morally or legally, 
to hide behind a misrepresentation of his paint when 
the paint is largely adulterated for the purpose of over- 
coming his ignorance in the manufacture. 


CHAPTER “I 


THE MANUFACTURE OF MIXED PAINTS 


THE modern methods of making mixed paint are 
‘divided into two classes, depending upon the specific gravity 
and fineness of the raw material. 

One of the methods employed is to mix the raw 
material with sufficient linseed oil to form a very heavy 
paste, the proper tinting material being added during 
the process of mixing. ‘This paste is then led down from 
the floor on which it is made, into a stone mill and 
ground. Even when the mill is water-cooled, the mass 
frequently revolves at such a speed that the paste paint 
becomes hot. It is then allowed to run from the mill 
into a trough called the “cooler,” or is stored in barrels 
to be thinned at some later time. In case the operation 
is continuous and the paste is thinned at once, it passes 
from a stone mill to a mixer below which contains the 
requisite quantity of thinning material composed of oil, 
volatile thinner, and drier, where it is intimately mixed 
by means of paddles. It is then compared with the 
standard for shade, and if the tone should not be identical 
with the former mixing, either tinting material or pigment 
is added in sufficient amount to produce the proper 
shade. From the last mixer, known as the “liquid 
mixer,” the paint is drawn off and filled into packages, 
the final operation before allowing it to enter the package © 
being to strain it. This method has been used ever 


since mixed paints have been made. The majority of 
6 


THE MANUFACTURE OF MIXED PAINTS 





No. 1. A MILL ror PAstE GrinvDING 


8 CHEMISTRY AND TECHNOLOGY OF PAINTS 


white paints, or paints of heavy specific gravity, are 
made in this manner. 

The paints of lower specific gravity, varnish and 
floor paints, are made differently. This method is really 
the reverse of the old-fashioned method, in that the 
liquid and pigment are placed in a mixer on an upper 
floor in the amounts necessary to produce the correct 
consistency. The paint is run down in a thin stream to 
the floor below into a mill known as the “liquid mill.” 
The liquid mills revolve very rapidly, the stones being 
flat. 

According to the best practice of making paste 
paints a grinding surface is supposed to be conical, 
although there is much difference of opinion on this 
subject. When the paint has run through the stones of 
a liquid mill, it comes out of a spout and is then ready 
for packing, due precaution being taken, however, to 
strain it twice, once as it passes down into the liquid 
mill and again as it flows out. There is much difference 
of opinion among paint-making mechanics as to the 
proper surface which a grinding surface shall present; 
for instance, the first depression in the stone of a mill 
is deep, tapering toward the edge, and is known as the 
“lead.” From the end of this ‘“lead”’ fine lines radiate 
toward the “periphery” of the stone. These are called 
the “drifts,” and the paints containing silica wear off 
the surface of even the hardest flintstone mills, so that 
in well-regulated factories a man is always employed 
sharpening the mills, and by the term “sharpening”’ is 
understood cutting out the “drifts” and “leads.” 

Not so many years ago paint mills were composed 
of either iron or steel, but in modern paint practice mills 
of this character have been abandoned, except for use 
as filling machines. They grind fairly fine when sharp, 


THE MANUFACTURE OF MIXED PAINTS 





No. 2. STANDARD LiquIp MILL. KENT. 


ge) CHEMISTRY AND TECHNOLOGY OF PAINTS 


but inasmuch as all silicious paint materials are harder 
than steel or iron they become dull in a very short time. 
Then again, the attrition grinds off small particles of 
iron, which affect all delicate tints more or less. 

The arrangement of the tanks and mills in the factory 
is of the greatest importance. Taking up first the 
second method of mixing paint already described, the 
liquid and white base are mixed in large, heavy cast- 
iron mixers, which are located on a platform high 
enough to discharge into a liquid mill. (See No. 4, 
Heavy Mixers.) 

The mixed material is ground through this mill and 
discharged from it into storage tanks situated con- 
veniently on a platform below the floor on which the 
mill is located, these storage tanks holding from 1500 
to 2000 gallons of the ground product. From the stor- 
age tanks a pipe-line with its various branches carries 
the paint to tinting tanks placed at convenient dis- 
tances from the storage tanks, the latter being high 
enough to allow the paint, by gravity, to flow through 
pipes to the tinting mixers. This pipe-line is made of 
wrought iron, the usual diameter of which is 4 inches, - 
the joints being all flanged so that the pipes may be 
easily taken apart and cleaned. 

Underneath the storage tanks and close to the outlet 
is a master valve, so that the product in the tank may be 
shut off at any time and the flow cut out from the sys- 
tem of pipes. Opposite each tinting tank (these tanks 
should be in parallel rows and numbered to correspond 
to the tints that are to be made) a 2-in. branch pipe is 
connected to the 4-in. main, and each of these branches 
is furnished with a valve to control the discharge into 
the tinting mixers. The cast-iron mixers already men- 
tioned should be so arranged that two mixers work in 


THE MANUFACTURE OF MIXED PAINTS 8 & 





No. 3. Mitt OPENED FOR CLEANING — Note design of grooves on upper stone. 


12 CHEMISTRY AND TECHNOLOGY OF PAINTS 


conjunction with one mill. The mill is of stone and 
known as a liquid or incased mill, the usual diameter 
being 30 to 36 inches. 


E 
BS oe earn Zaye SESS ae ASE TS ee, GL See TI 


TROBE SSG G i SEN EES OME BS SSIES GG 















aii mais \ 












TINTING TANKS 











eee: vue sabia Patri st : 


No. RTE MIXERS 


The storage tanks are made of sheet metal with 
heavy sheet-steel bottoms, and are furnished with a 
slowly revolving stirrer to keep the ground liquid agi- 
tated. The outlet of these tanks is of generous size and 
covered with a steel wire screen to prevent any foreign 


THE MANUFACTURE OF MIXED PAINTS 





No. 5. CHANGE-CAN PASTE Mixer— The can and the paddles 
revolve in opposite directions. 




















Cooren — 
— JF. Ye — 
ara Lice 
2 a Sy A 
coven Mice: 
YEE 
x ~~ (a: ih 
{ {- 
t—T hor } 
|__| 
OLN GA / 
cases 


No. 6. 


















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= 


u 
ols ml 
hd Bp 


H 
2 
yp drt 





- 






































THE MANUFACTURE OF MIXED PAINTS 15 


matter such as chips of wood or like material from getting 
into the supply pipes. Fastened to the stirrer of these 
tanks is a wire brush which scrapes the surface of the 
screen in its rotation around the tank, thus keeping the 
holes of the screen free for the proper flow of the liquid. 
The tinting colors used in this process are usually ground 
through small stone mills of 15 in. or 20 in. diameter, 
and are stored in convenient portable receptacles. 

This method of liquid paint-making reduces the 
handling and labor cost to a minimum, the hardest work 
being done on the mixer platform where the dry pigment 
and the proper amount of liquid are first mixed. In a 
factory where the floors are not arranged so that the 
method already described can be carried through by 
gravity alone, it is possible and practicable to introduce 
a force pump, preferably of the rotary type, to make up 
for this deficiency. When this latter method is _ used, 
the cast-iron mixer and mill should remain in the same 
relative position as before, but the storage tank could be 
placed in any other part of a building and on the same 
floor as the liquid mill, but high enough to discharge 
by gravity into the tinting mixers. The ground pig- 
ment would then be discharged into a small tank 
situated at the foot of the mill, to which the rotary pump 
is attached. As this tank is filled with the ground 
product, the pump would force it through the proper 
pipe connection to the storage tank, the connection 
from the storage tanks to the tinting mixers being the 
same as in the first described process. 

The other method in use is to mix and grind the 
pigment in paste form, using the same style of mixer; 
but instead of a liquid mill a paste mill is used. Situated 
at the back of this paste mill, and close to the discharge 
scraper, is a steel tank of generous dimensions (usually 


16 


CHEMISTRY .AND TECHNOLOGY OF PAINTS 







4TH FLOOR 














(eee | ae —S 
| eS eS 









a: 
l 


: 





THE MANUFACTURE OF MIXED PAINTS 17 


soo gallons), into which the ground pigment is dis- 
charged. This steel tank is provided with a stirrer for 
mixing the ground pigment with the oil and other thin- 
ners that are added to it, in order to reduce it to a 
liquid form. It is then carried to the tinting tanks by 
a pipe-line on the same general plan as that heretofore 
described. 

One of the advantages of this plan is that this outfit 
can be used in a dual capacity, i.e. it can be used for 
the mixing of liquid paints after the plan described and, 
by changing the scraper from the back to the front of 
the mill, the outfit can be changed into a paste-grinding 
plant. 

Many paint factories are located in one-story buildings. 
In this case the steel thinning tank as described above is 


oe cece (een ee eae oo qiqusee—= ae 


ae x 8 Pulley 


jl 





~\\ 


—=-=--6' ('----=+ 


----------------]3!. §''------- 


‘hohe Capacty 
pproximately 
150 Lb/Sq. Ft. 


SN 


20"High 
Leg Mill-----> 


------7'. 6'"\------- 


CEG 


7 YY 


No. 8 A SINGLE Story PAINT FACTORY 


furnished with casters, or lift trucks are used in order that 
it may be moved to a stationary paddle equipped with a 
propellor blade, the shaft of which may be raised vertically 
to allow the tank to be placed underneath. The mixer 
is placed on a platform just above and behind the mill, 


18 CHEMISTRY AND TECHNOLOGY OFSPATH TS 


or if the building is not high enough, change can mixers 
are used and the heavy cans moved around by means of 
an overhead trolley track on which a chain fall travels. 
Containers for the finished paint are filled from the thinning 
tank which is generally about 125 gallons capacity and 
fitted with a gate at the botton for the purpose, by hoisting 
it with this tackle or by raising it on a portable elevator. 
One-story paint factories are always more or less of a make- 
shift nature and are only designed from necessity for 
financial reasons, as the enormous amount of waste motion, 
time and extra labor makes them very inefficient. 


PEBBLE MILLS 


The pebble or ball mill has come into use in recent 
years and because of its advantages is a most efficient 
means of grinding many types of paint, particularly those 
that do not require extremely fine grinding and the ones 
that contain dry ingredients requiring little grinding by 
reason of their soft texture. 

The mill consists of a revolving steel conde of rugged 
construction mounted on trunions and lined with burrstone. 
It is about half filled with flint pebbles and the sliding, 
rubbing and grinding action of these pebbles on each other 
and against the cylinder wall grinds pigment and vehicle 
into a uniform product. All the materials are loaded at 
once into an opening from the floor above or from a plat- 
form and the finished paint is filled into containers or 
pumped into storage tanks from a valve which is located 
opposite the filling cover. 

Pebble mills have many advantages over the older 
types of mill. Whenever the same result may be obtained 
in less time than by the use of flat stone or roller mills 
there is obviously a great saving. Labor is also saved by 
combining the three operations of mixing, grinding and 


THE MANUFACTURE OF MIXED PAINTS 1Q 





No. g. PEBBLE MILL SHOWING METHOD OF CHARGING 


20 CHEMISTRY AND TECHNOLOGY OF PAINTS 


thinning, and in the slight attention the mill requires while 
in operation. There is little heating or evaporation and 
both the grinding room and the paint are kept cleaner. 
Although their makers recommend them for the manu- 
facture of almost every kind of paint and while they are 
capable of making most of them, they have by no means 
entirely supplanted the other types at the present time, 
most of their users preferring to limit them to certain 
varieties of paints and to continue the use of the older 
types for others. They cannot be employed where a stiff 
paste is required, as they will only make a semi-paste and 
they are not generally suitable for the production of small 
batches. The most efficient sizes are 6 to 8 feet or more 
in diameter having capacities of 400 to 1800 gallons of paint. 


A Pebble Mill cylinder may be considered as an elevator carrying 
the material to the top of an incline down which it will tumble with 
more or less speed according to the slope of the dump. 





In No. to shown above is indicated in black a wedge-shaped 
block of material ready to slide down and in No. 11 is shown the 
same wedge after falling. It is to be understood, however, that 
while these figures are theoretically correct as a basis of calculations, 
the actual outline of thick or dry material in the revolving cylinder 
will be about as indicated in No. 12 for the reason that the cen- 
trifugal force will be stronger at the circumference than near the 
center and because of the rebound and deflection at the bottom. 

In dropping the pebble has an accelerated movement so that its 
first contacts have less force than later ones which explains the 
greater pulverizing effectiveness of mills having large diameters as 
compared to mills of small diameter and also shows why mills must 
not be built so large as to have a destructive effect on the pebbles 
themselves. — Courtesy Paul O. Abbé, Inc. Copyright, 1924. 





THE MANUFACTURE OF MIXED PAINTS 





21 





No. 13. A ROLLER MILL 


22 CHEMISTRY AND TECHNOLOGY OF PAINTS 


The size of pebbles varies in ratio to the capacity of 
the mill. Large mills have large pebbles and small mills 
have small pebbles. It must be taken into account that 
the attrition or grinding of paint is produced entirely by 
the impact of one pebble on another, so that if pebbles are 
too large, longer time is necessary in grinding, and if they 
are too small, the weight is insufficient. 

There is another point with regard to the pebbles which 
must always be taken into account. After a mill has run 
a year, the pebbles are very much reduced in size, for it is 
quite natural that the surface is abraded. For each charge 
of paint, the distribution of added silica from this cause is 
not very great but it is a factor just the same. 


ROLLER MILLS 


Roller mills are often used for the manufacture of mixed 
paints and enamels but their principal use is in the manufac- 
ture of printing inks. They are much more rapid than the 
flat stone mills but do not grind so fine, the paint being put 
through the mill several times to produce the same effect as 
that produced by one run through a burrstone mill. This 
multiple grinding is often accomplished by placing two or 
three such mills one above the other so that the paint flows 
directly from the outlet of one onto the rolls of the next. 

The mill usually consists of three steel rollers so mounted 
on supports that the paste, flowing in a continuous stream 
from a gate in the side of the mixer which is always mounted 
above the mill, drops between the first and second rollers, 
is ground between them and then goes between the second 
and third where it is scraped off by the delivery trough. 
The first and third rolls are often hollow, especially in the 
larger sizes, to allow for cooling by the circulation of water 
through them. In England they are more popular for 
paint grinding than they are here. 


THE PIGMENTS 


CHAPTER II 


THE WHITE PIGMENTS 


THE white opaque pigments used in making mixed 
paints are white lead, zinc oxid, sublimed white lead, 
leaded zincs, lithopone, and other zinc and_ lead 
pigments. 

Among the white leads there are several varieties; 
the principal ones, however, are the old Dutch process 
lead and the quick process lead, both of which are 
hydrated carbonates of lead. 

There are many varieties of zinc oxid made in the 
United States, depending largely upon the raw material. 
The grade made principally from spelter, according to the 
French process, is known in America as “Florence Red” 
and ‘“‘Green Seal Zinc.’”’ The seals on zinc indicate the 
whiteness of color, the green seal being the whiter. In 
Germany the colored seals extend to a greater range 
than in America, the green seal being the whitest, the 
Ted next, the blue next, the yellow next, and then the 
white. 

The New Jersey zinc oxids are made direct from the 
ore and are almost as pure as the zincs made from the 
metal, but they have a totally different tone, being much 
more of a cream color than the so-called French zincs. 

The Mineral Point zincs made in Wisconsin contain 


a varying percentage of sulphate of lead. The leaded 
23 


24 CHEMISTRY AND TECHNOLOGY OF PAINTS 


zincs of Missouri are analogous in composition to those 
of Mineral Point, but the percentage of sulphate of lead 
is much higher. 

Sublimed white lead is made in Joplin, Missouri, 
from Galena mineral, and will average 95 per cent 
oxysulphate of lead and 5 per cent zinc oxid. ‘This 
material has been largely superseded by a white known 
as Ozark White, which is described under that heading. 
Leaded zincs are similar to Ozarks. | 

Lithopone is a double precipitate of sulphide of zinc 
and sulphate of barium. 

These are the opaque white pigments used in the 
manufacture of mixed paints. It is not within the power 
of any man to say which one of these is the best, because 
under certain circumstances one material will outrank 
another, and long practice has demonstrated that no 
single white pigment material is as good as a mixture of 
various white pigments for mixed paint. The differences 
of opinion and conflicting reports that one hears con- 
cerning these raw materials are largely due to competi- 
tion among manufacturers. Whenever a new material 
is exploited a manufacturer of a tried and staple pig- 
ment naturally finds the defects in the new material 
and informs his salesmen to this effect. And so when a 
material finally succeeds and takes its place among the 
recognized list of pigments it has gone through all the 
hardships and vicissitudes possible. 

For two thousand years, more or less, there was no 
other white pigment than white lead. Within the life- 
time and memory of many a paint manufacturer in the 
United States all the pigments described in the beginning 
of this chapter have been born and have prospered. 
The great competitor of white lead is zinc oxid, and the 
weakness of white lead is the strength of zinc oxid, and 


WHITE PIGMENTS 25 


vice versa. White lead, for instance, is a soft drier and 
zinc oxid is a hard drier. White lead finally becomes 
powdery; zinc oxid in its eventual drying becomes hard, 
and it is for these reasons that a mixture of zinc oxid 
and white lead forms such a good combination. On the 
other hand, it is regarded as a fact that a paint com- 
posed of an opaque white pigment in a pure or undiluted 
state should not be used, for experience and chemistry 
have both shown that an inert extender added in mod- 
erate proportions to the solid white pigment increases 
its wearing power, and when the surface finally needs 
repainting it presents a better foundation for future 
work. ‘Taking all of these facts into consideration, a 
paint manufacturer who combines experience with the 
teaching of chemistry is quite likely to produce a mate- 
rial that will add both to his reputation and his income. 
He certainly has a great advantage over the man who 
works entirely by rule of thumb. 


WHITE LEAD 
Formula, 2PbCO;:Pb(OH)2; Specific Gravity, 6.323 to 6.492 


White lead is the oldest of all white paints, and prior 
to the middle of the last century it was the only white 
pigment in use with the exception of a little zinc and bis- 
muth. Within half a century quite a number of other 
white pigments have come into use, and only gradually 
have the defects of white lead become known. However, 
paint manufacturers in the United States are very large 
users of dry white lead, which, together with zinc, 
asbestine, and other inert materials, forms the bases or 
pigments of the mixed paints. There seems to be an 
antagonism against the use of white lead which apparently 
is unfounded, for, although white lead may have its 


26 CHEMISTRY AND TECHNOLOGY OF PAINTS 


defects, there is no other white pigment which is 100 
per cent perfect, and therefore it is only fair to give that 
time-honored material its proper due. White lead as a 
priming coat on wood, particularly when it contains 
more oil than should normally be used, cannot be ex- 
celled. 

The history of this pigment, its method of manu- 
facture, and the general uses to which it has been applied 
are so well known, and are 
generally given even in 
elementary text-books on 
chemistry, that it is not 
the author’s purpose to 
take up much space for 
this subject. Briefly stated, 
however, there are two 
processes for the manu- 
facture of white lead. One 
is called the Dutch process, 
which takes about ninety No. 14. Corropep Warre Leap— 
days and is a slow cor- Photomicrograph X250, of known 

: purity and composition. 
rosion of a buckle of lead 
in an earthenware pot in the presence of acetic acid. 
Carbonic acid from fermenting tan bark acts on the 
lead, converting the material into hydrated carbonate 
of lead. In the other, which is called the quick 
process, the acetic acid solution is directly acted upon 
by either carbonic acid gas or an alkaline carbonate 
salt. The old Dutch process is still much more largely 
used than the quick process, the resulting product being 
much more desirable from the practical standpoint. 
There are a number of other processes under a variety 
of names, but none of them differ very much from the 
so-called ‘quick process.”’ 





WHITE PIGMENTS 27 


White lead is in great favor with the practical painter, 
not for its wearing quality, but principally for the free- 
dom with which it is applied. Although white lead is 
generally spoken of as a carbonate of lead, it is com- 
posed of approximately 69 per cent carbonate of lead, 
PbCO;, and 31 per cent of lead hydroxid, Pb(OH).. 
It is this lead hydroxid which combines quite rapidly 
with oil and forms an unctuous substance sometimes 
known as “lead soap.” 
White lead is variable in 
composition, the amount 
of hydroxid ranging from 
TRL hed Om Clee COOL tel Ty 
addition to this, during 
the process of manufac- 
ture of the old process 
leads and -aiter its) tinal 
washing, it is mixed with 
linseed oil while still in 
the wet state. The. oil 
having a greater affnity 
for the white lead than 
the water has, the latter is displaced. A -small per- 
centage of moisture adds to the free working quality of 
the paint made from white lead. (See ‘‘Water in the 
Composition of Mixed Paints,” page 286.) 

White lead is regarded as a poisonous pigment, and 
so it is, but this property should not condemn it for 
application to the walls of a house or for general paint 
purposes, because its toxic effect cannot be produced 
from a painted surface. Its poisonous quality is mani- 
fest to the workmen in the factories where white lead is 
made, and also to the painter who is careless in apply- 
ing it. The unbroken skin does not absorb lead very 





No. 15. OLp Process WHITE LEAD — 
Photomicrograph x250. 


28 CHEMISTRY AND TECHNOLOGY OF PAINTS 


rapidly, but the workman inhaling lead dust, or the 
painter who allows a lead paint to accumulate under his 
finger nails, is likely to suffer from lead poisoning. In 
one or two factories where much white lead is ground, a 
small percentage of potassium iodide is placed in the 
drinking water. This overcomes any tendency toward 
lead poisoning, by reason of the fact that the soluble 
iodide of lead is formed in the system and the lead is 
thus flushed out through 
the kidneys. Charles Dick- 
ens, in one of his short 
stories called “A Bright 
Star in the East,” com- 
ments on the misery pro- 
duced in a certain white 
lead factory in London, 
and expresses the hope 
that American ingenuity 
would overcome the dan- 
gers which beset the men. 
In one of the largest white 
lead works in New York 
City lead poisoning does not occur, owing to the in- 
genuity and care exercised by the management. 

The ratio of oil necessary to reduce white lead to the 
consistency of paint can by no means be given in exact 
figures. The old Dutch process lead will take four and a 
half gallons of linseed oil to one hundred pounds of white 
lead ground in oil, in order to obtain a paint of maxi- 
mum covering property. The new process lead will take 
more oil than this, and in many instances up to six 
gallons to the one hundred pounds of white lead paste, 
which contains approximately 1;’'> gallons of linseed 
oil. On a mixed paint basis, 60 pounds of dry white 








No. 16. WuIte LEAD (new process) — 
Photomicrograph X250. 


WHITE PIGMENTS 20 


lead will take 40 pounds of linseed oil to produce the 
correct ratio, but in addition four pounds of volatile 
thinner, such as benzine or turpentine, can be added to 
increase the fluidity and assist in the obliteration of 
brush marks. No general rule can be given for the per- 
centage of oil necessary, as temperature has much to do 
with this, but the difference in the amount of oil neces- 
sary to produce a good flowing paint during summer or 
winter can be approximately given as ro per cent, less 
vehicle being necessary in summer than in winter. 

White lead when exposed to the elements becomes 
chalky after a while and assumes a perfectly flat appear- 
ance which resembles whitewash, and comes off very 
readily on the hand. As long as there was no remedy 
for this there was no comment on the subject, but at the 
present time investigators have improved paint mixtures 
so that this defect is not so palpable as it was in former 
years. From many experiments made by the author 
the causes of the chalking of white lead may be sum- 
marized as follows: 

Normal lead carbonate which contains practically no 
hydroxide and which is so often confused for white lead 
is crystalline material having little or no hiding power, and 
is composed entirely of boat-shaped crystals. When 
litharge is carbonated under pressure, with carbon dioxid, 
it is converted into a white crystalline mass which must 
not be mistaken for white lead, which is a pure lead car- 
bonate. These boat-shaped crystals were formerly very 
evident, even in white lead of commerce, but at the present 
time white lead is so scientifically manufactured that 
these boat-shaped crystals are seldom, if ever, seen. 

One of the defects mentioned by many writers on 
white lead is its susceptibility to sulphur gases. In 
nature these sulphur gases are generated in two places; 


30 CHEMISTRY AND TECHNOLOGY OF PAINTS 


namely, in the kitchen of every house, and in and around 
stables and outhouses. In kitchens the cooking of 
vegetables liberates hydrogen sulphide to a great extent, 
the odor of which is familiar to everybody who comes into 
a house where either cauliflower or cabbage is being 
cooked. But, inasmuch as undiluted white lead is not 
often used for interior painting, the defect is not so 
noticeable. Few stables or 
outhouses are painted pure 
white, and when they are 
painted white the painter 
generally has sufficient 
knowledge of the subject 
to use zinc oxid instead of 
white lead. 

It cannot be denied 
that the ease of applica- 
tion of white lead, as well 
as its enormous covering 
property, has had much to 
do with the preference for 
No. 17, LEap CARBONATE CrysTAIs— ft ag q paint. With the ex- 

page aes 4S ception of lithopone, it has 
a greater hiding property, volumetrically considered, than 
any other white paint; on the other hand, gravimetrically 
considered, it has less body than any of the lighter paints. 

The addition of an inert filler, such as artificial barium 
sulphate, silica or barytes, improves white lead con- 
siderably. These inert fillers, which will be considered 
under their proper headings, are not affected by chemical 
influences in the slightest degree, and where they are 
used in the proper proportions additional wearing quality, 
or “life,” as the painter calls it, is given to the paint. 
The percentage of inert fillers which can be added to 





WHITE PIGMENTS 31 


white lead varies up to 50 per cent. More artificial 
barium sulphate than natural barium sulphate can be 
added: If a comparative exposure test be made, both 
on wood and metal, of undiluted white lead and white 
lead containing an inert extender, it will be found that 
at the end of eighteen months the paint which contained 
the filler is in a better state of preservation than that 
which did not contain it. Generally considered, white 
lead is an excellent paint, more particularly when added 
to other materials. 


SULPHATE OF LEAD 


Formula, PbSO,; Specific Gravity, 6.2 to 6.38 


It must be borne in mind that the sulphate of lead 
of commerce, which is not so frequently met with nowa- 
days as formerly, is a very poor paint material, and it 
must not by any means be confounded with sublimed 
white lead, which is at times erroneously called lead 
sulphate. 

The lead sulphate of the paint trade is a nondescript 
article which was sold as a by-product by the textile 
printers who used acetate of lead as a mordant. Sul- 
phuric acid was added to this liquid and the precipitate 
was. sold to the paint trade under the name of lead 
bottoms or bottom salts. Occasionally this material is 

still met with, and wherever it is used in a mixed paint it 
does more harm than good. It is likely that the pure neutral 
lead sulphate, which is a good oxidizing agent and which 
dries well, and covers fairly well, could be used for ordi- 
nary light tints if diluted with the proper inert materials, 
but the lead sulphate which is sold by the textile printers 
is always acid and is sometimes coarse and crystalline, 
though at other times quite fine. The chemist, the paint 


32 CHEMISTRY AND TECHNOLOGY OF PAINTS 


maker and the engineer must never confound this lead 
sulphate with the lead sulphate contained in sublimed 
lead, zinc lead or leaded zincs. 


SUBLIMED WHITE LEAD 
Specific Gravity, 6.2 


Sublimed white lead is an amorphous white pigment 
possessing excellent covering and hiding power, and is 
very uniform and fine in grain. It is a direct furnace- 
product obtained by the sublimation of Galena, and 
within the last ten years it has come into great prom- 
inence among paint makers, now being regarded as a 
stable, uniform, and very valuable paint pigment. The 
author has examined a great many paints containing 
sublimed lead. Among one hundred reputable paint 
manufacturers in the United States sixty-five used sub- 
limed lead. About eight thousand tons were used in 
the United States in 1905. Considering the face ana: 
sublimed lead as a pigment is about twenty-five years 
old, it is very likely, judging from its qualities, that it 
will be used more universally and in larger quantities 
in the future. 

When mixed with other pigments, such as zinc oxid, 
or carbonate of lead, and the proper reducing materials 
added, such as silica, clay, barium sulphate etc., it pro- 
duces a most excellent paint and at the seashore its 
wearing quality is superior to that of carbonate of lead. 
In composition it is fairly uniform. From the analyses 
of thirty-four samples of sublimed lead its composition 
may be quoted as 75 per cent lead sulphate, 20 per cent 
lead oxid, and 5 per cent zinc oxid, although each of 
these figures will vary slightly either way. Corroded 
white lead also varies in its percentage of hydroxid, but 


WHITE PIGMENTS =e 


for analytical purposes a constant must be admitted 
which will fairly represent the composition. 

The question has arisen of late years whether sublimed 
lead is a mixture of the three components just cited, or 
whether it is a combination of lead sulphate and lead 
oxid with the mechanical addition of zinc oxid. Inas- 
much as all the lead oxids that are known in commerce 
or in chemistry are yellow, red, or brown it is held by 
many that the lead oxid 
of sublimed lead is really 
an oxysulphate, or, in 
other words, a basic sul- 
phate of lead. A mixture 
of precipitated lead sul- 
phate, litharge, and zinc 
white in approximately the 
proportions found in sub- 
limed lead, when ground 
in oil and reduced to the 
proper consistency, dries 
totally different from sub- 

No. 18. SUBLIMED LEAD X500. limed white lead; in fact, 

sublimed lead when ground 
in raw linseed oil takes two days to dry dust free, but the 
mixture just cited will dry sufficiently hard for repaint- 
ing in twelve hours, because lead sulphate is a fair drier 
and lead oxid a powerful one. Yet the oxysulphate, hav- 
ing the same composition, behaves totally different from 
the mixture and in addition is of a different color. 

Under the microscope sublimed lead shows an absence 
of crystals and remarkable uniformity of grain. Being a 
much more inert chemical body than the other lead 
pigments, it does not react on linseed oil and _there- 
fore makes a much more durable paint compound. It 





34 CHEMISTRY AND TECHNOLOGY OF PAINTS 


has been urged that sublimed lead is not as susceptible 
to sulphur gases as white lead, but this the author 
has not been able fo substantiate, for while it may take 
hydrogen sulphide a longer time to discolor it, it is 
simply a question of degree and it is acted upon by sul- 
phur gases, although not as quickly as white lead. 

Sublimed lead can be determined in a white mixed 
paint without any difficulty, owing to the established 
ratio between lead oxid and lead sulphate. The per- 
centage of free zinc sulphate in sublimed white lead 
varies from a trace to a’half per cent, and many times a 
chemist will report more zinc sulphate than is actually 
present, because in washing or boiling a dry or extracted 
sample the lead sulphate may interact with the zinc 
oxid and show a larger percentage of zinc sulphate than 
is really present in the dry products before analysis. 

Sublimed white lead as a marine or ship paint is of 
much value, owing to its hardness of drying and imper- 
viousness of film. 


OZARK WHITE 


Ozark White is a very desirable pigment and has all 
of the good qualities of Standard Zinc Lead White and 
Sublimed White Lead. It is very largely used in the 
manufacture of mixed paint. In many respects it is 
superior to the old Standard Zinc Lead White, because 
its approximate composition is 60 per cent of zinc oxid 
and 40 per cent of lead sulphate. 

The process is so highly perfected that the manu- 
facturers can control the composition so as to insure a 
variation of not over 2 per cent, and with rare exceptions 
the material does not vary 1 per cent from the composition 
given. To attain this degree of uniformity, a complete 
analysis of every car of ore is made as soon as it is received 


WHITE PIGMENTS 35 


before passing it to the mechanical mixers. At the mixers 
another analysis is made, and an ore higher in zinc or lead 
added, as the case may require, in order to have the proper 
metal constituents. The ore, after being mixed with the 
proper proportion of coal and antifluxing material (crushed 
silicious rock or mine screenings), is charged into furnaces 
which have previously been bedded with a sufficient amount 
of coal to start combustion. The furnaces are then sealed, 
allowing the temperature 
to rise to about 2300 F., 
at which point it is held 
until the zinc and lead pass 
off together in the form of 
fume, which is conducted 
by means of suction fans ee 
through pipe-lines for a 
distance of about 500 feet, 
where it enters large brick 
bag houses. The fumes 
have by this time lost con- 
siderable of the heat, so 
that they may be gathered 
into fabric bags, where the gases pass out and the pigment 
is collected. From the bag house the pigment is conveyed 
to an automatic packer and placed in barrels of suitable 
weight, and is then ready for the consumer. 

An actual chemical analysis of an average type of 
Ozark White shows the following: 





No. 19. Ozark WuitE—Photomicro- 
graph 300. - 


Piet Pah he es, a fea ng BS 50182 pet oa 
Pi S Glo > a ESI aie ena ee ar pegs 26.05 

MN Rg St) fn ted Oo ae 
TSlolsn © coll ARG snk i Rei aN alee Gion yr aeage 
Me ee sc a patois Pee er ak Sour stat 
RP aes I len ie nash Oe ek a oe ae ake 





Total 99.98 per cent 


36 CHEMISTRY AND TECHNOLOGY OF PAINTS 


ZINC OXID 


Formula, ZnO; Specific Gravity, 5.2 


Zinc oxid as a paint pigment is only sixty years old, 
and when it is taken into consideration that in that short 
space of time its use has grown until in 1905 nearly 
seventy thousand tons were used in the paint industry 
in the United States, it speaks for itself that the material 
must be of exceptional merit to have advanced so rapidly. 
At the same time, although it is impossible to obtain any 
exact figures on the subject, it is probable that more than 
one half of these seventy thousand tons was used in con- 
nection with other materials. 

The discovery of zinc oxid by Le Clair in France and 
Samuel T. Jones in America is sufficiently well known, 
and has been quite thoroughly written up in other books. 
The former made zinc oxid by subliming the metal; the 
latter made it by subliming Zincite and Franklinite ores. 
The specific gravity of zinc oxid will average 5.2, and 
fifty pounds will take fifty pounds of linseed oil; in other 
words, to produce the proper mixed paint it will require 
a far greater proportion of linseed oil than white lead 
will take. It is generally stated in text-books that zinc 
oxid is not affected by sulphur gases and _ therefore 
will not turn color. This statement is not exactly correct; 
the author always contended that zinc oxid is not visibly 
affected by sulphur gases, but there is no doubt, as any 
chemist will admit, that zinc oxid is affected by sulphur 
gases, although not to~the same extent as white lead. 
As zinc sulphide, zinc sulphite, and zinc sulphate are 
white products, the adsorption is not evident to the eye, 
and hence the erroneous statement has crept into use that 
zinc oxid is not affected by sulphur gases. 


WHITE PIGMENTS 37 


When mixed with linseed oil and the proper amount 
of drier, it sets and dries much more slowly than white 
lead. Nevertheless this drying continues in the form of 
progressive oxidation until the surface becomes very hard. 
A comparison between zinc-oxid and white-lead paints 
will show that the progressive oxidation which takes 
place when white lead dries produces a chalky mixture, 
while the reverse is true of zinc oxid, which will produce 
a hard and brittle vitreous surface which is somewhat 
affected by temperature changes. Owing, therefore, to 
the diverse effects of the two pigments, a combination 
of lead and zinc is often well recommended. The hard 
drying of zinc has not, however, been very well understood. 
Fifteen years ago the author undertook a series of experi- 
ments and found that the drier was very largely respon- 
sible for the hardening action of zinc. If the linseed 
oil be prepared with litharge (PbO), the resulting zinc 
paint will last far longer and be much more flexible and 
consequently not readily cracked when exposed to a 
variation of temperature of even 130° F., such as we have 
in this climate. If, however, a drier is used in which 
manganese (MnO.) and red lead (Pb;O,) have been cooked 
with the oil, the action of the manganese continues until 
a vitreous surface is the result. It is owing to the result 
of these investigations that the use of American zinc 
oxid made from Franklinite ore has become so general 
for the manufacture of white table oilcloths. (See Journal 
of Society of Chemical Industry, No. 2, Vol. XXI, 
Jan. 31, 1902.) 

When enamel paints are made of an oil varnish and 
zinc oxid, and the drier in the varnish is composed of 
manganese and lead, the enamels eventually become 
hard, evidently through the catalytic action of the man- 
ganese. It is desirable to omit the manganese in high 


38 CHEMISTRY AND TECHNOLOGY OF PAINTS 


grade enamels, or, where manganese must be used in 
order to obtain a rapid setting, the borate of manganese 
should be employed, but only in very small quantities. 

The American zincs are: 

First. The Florence Red and Green Seal zincs, which 
are made by the sublimation of the metal and are prac- 
tically pure and equal in all respects to those made in 
France and Belgium. 

Second. Tne New 
Jersey zinc _ oxids, 
which are made from 
Franklinite ore and 
are free from lead 
and frequently run 
over 99 per cent ZnO. 

Third. Mineral 
Point zinc, which is 
made at Mineral 
Point, Wisconsin, 
and contains from. 2 


to 4 per cent of lead 
No. 20. AMERICAN WHITE SEAL ZINC OXxIDE— 
Photomicrograph x510 98.5 ZnO made direct sulphate. 
from the ore. Very fine material of uniform Fourth. The 
grain. Dry specimen. 





leaded zincs made in 
Missouri, which contain from 4 to to per cent of sulphate 
of lead. 

- Zine oxid chalks to some extent in the same manner 
as white lead, but only if the atmosphere is charged with 
carbon dioxid or salt. The same experiment which was 
carried out with white lead in order to show its solubility 
in a solution of carbon dioxid was carried out with zinc 
oxid and the same result obtained. Much weight cannot 
be given to these experiments, because these chemicals 
are not always present in the atmosphere. They are 


WHITE PIGMENTS 39 


merely chemical results which demonstrate both the 
cause and effect, but it is of some interest to know why 
the paint films perish. The zinc oxids made from western 
ores are slightly more permanent than those made from 
the New Jersey ores, and as paint materials they possess 
the advantage of containing a larger quantity of lead 
sulphate. | 

Nearly all zincs contain a small percentage of zinc 
sulphate. Much unnecessary trouble has been caused 
by the criticism against zinc sulphate. Where a paint 
contains moisture or where 
water is added in a very 
small amount to a heavy 
paint in order to prevent 
it from settling, and not 
more than one per cent of 
actual water is contained 
in the paint, zinc sulphate 
formes an excellent drier, 
particularly where it is de- 
sirable to make shades 
which contain lampblack. 
The outcry against zinc sul- : : 
phate is unwarranted, No. 21. American Wuire Seat Zinc 
because as much as 5 per OxIDE X510. Ground in oil. 
cent is used in making a patent drier. The amount 
of zinc sulphate, however, in most of the dry zinc 
pigments probably decreases with age. Zinc oxid or 
other zinc paint which will assay 1 per cent of zinc sul- 
phate will, when kept in storage for six months, show 
a decrease in the zinc sulphate to one half of 1 per 
cent. 

In the enamel paints the presence of zinc sulphate is 
not a detriment, and in floor paints it might be considered 








40 CHEMISTRY AND TECHNOLOGY OF PAINTS 


as a slight advantage, for it aids in the drying and harden- 
ing. However, too much of any soluble salt 1s never to 
be recommended. 
ZINOX 

This is a hydrated oxid of zinc not manufactured in 
this country, but made and used almost entirely in 
France. It is not yet sold dry, but generally sold either 
in the form of a ready mixed enamel or in a semi-paste 
form, and is presumed to possess advantages over zinc 
oxid. From experiments which the author made it has 
been found that the hiding power and working quality 
are practically the same as that of zinc oxid. It pos- 
sesses, therefore, no marked advantage over a zinc oxid 
enamel, although it is stated that it remains in sus- 
pension longer than any other pigment. The zinc oxid 
enamels all remain in suspension a very long time, and 
even though they settle they do not settle very hard and 
can be very easily stirred. In thinner media, such as 
are used for the manufacture of flat wall paints, the 
hydroxid of zinc has some advantage over the oxid, as it 
produces a paint that remains in suspension longer and 
is more ready for use than that made from the oxid. 


LITHOPONE 


Synonym: Oleum White, Beckton White, Charlton White, Ponolith, 
Jersey Lily White, Orr’s White, Albalith, etc., etc. 


Chemical Formula, ZnS + BaSO,; Specific Gravity, 4.2 


When solutions of zinc sulphate and barium sulphide 
are mixed together in molecular proportions a heavy 
flocculent precipitate is formed according to the following 
reaction: ZnSO, + Aq + BaS + Aq = ZnS + BaSO, + HO. 
The theoretical percentage will be about 29.5 per cent 
zinc sulphide and 70.5 per cent barium sulphate. This 


WHITE PIGMENTS AI 


precipitate as such has no body or covering power, and 
when washed and dried is totally unfit for paint pur- 
poses; but John B. Orr, of England, in 1880 discovered 
that when it is heated to dull redness, suddenly plunged 
into water, ground in its pulp state, thoroughly washed 
and dried, its characteristics are totally changed, and it 
-makes a very effective and durable pigment for paint 
purposes. In the first place, it is then a brilliant white; 
in the second place, it is extremely fine in texture; and 
in the third place, it has more hiding power than pure 
zinc oxid. Owing to its chemical composition it is stable 
in every medium known for paint purposes, excepting 
those which are highly acid. It took several years to 
perfect the manufacture of lthopone, but it may be 
easily said that at the present time lithopone is made 
with great uniformity and has valuable properties, as 
will hereinafter be shown. 

The method of manufacture is quite simple, success 
depending very largely on the purity of certain materials. 
It is worthy of mention, however, that the average chem- 
ist unfamiliar with both the theory and practice of its 
manufacture cannot make it successfully. In the first 
place, solutions of barium sulphide and zinc sulphate of 
known composition must be made. The fact that they 
are impure has no effect on the ultimate product, provided 
the chemist knows the impurities he has to deal with 
and the simple methods for their elimination. For 
instance, the zinc sulphate must be free from iron, or a 
yellowish product is the result. The solutions must be 
standardized for each batch. The impurities can be 
eliminated during the process of manufacture, or, more 
properly speaking, before they are pumped into the pre- 
cipitation tub. 

The barium sulphide, however, is quite pure, for the 


42 CHEMISTRY AND TECHNOLOGY OF PAIN ys 


reason that metals like copper, iron, and manganese 
which are likely to be present, form insoluble sulphides. 
Barium sulphide is made by heating barytes (BaSO,) to 
dull redness with coal, petroleum residuum, pitch, saw- 
dust, or other materials having a high percentage of 
carbon. The resulting reaction may be represented by 
the following equation: BaSO, + 4C = BaS + 4CO, al- 
though under many circumstances the reaction is more 
slightly complicated. After the reaction is completed and 
before the air can have any influence on the sulphide, the 
mass is digested in vats and filtered; when the solution 
reaches a density of 17° Baumé, long, yellowish, needle- 
shaped crystals separate from the mother liquor. These 
crystals are almost chemically pure barium sulphide. 

Re adh With the proper con- 
centration of the solu- 
tions, proper tempera- 
ture and speed at which 
the two solutions are 
poured together, the re- 
sulting precipitate will be 
of such physical charac- 
teristics that it can be 
most easily filtered and 
dried. It is then placed 
No. 22. LirHopone (dry) —Photomi- in muffles and _ heated 

crograph X250, exceedingly fine and above 920° Fahrenheit, 
uniform in grain. 
suddenly plunged into 
water, again ground, washed, and dried. It is then ready 
for the market. Overheating of the precipitate decom- 
poses some of the zinc sulphide and converts it into 
zinc oxid. All of the earlier manufacturers overheated 
their product, and that is the reason why lithopone formerly 
contained from 5 to to per cent zinc oxid, whereas theo- 





WHITE PIGMENTS 43 


retically it should have contained none. The manu- 
facturers of the present day, however, have overcome all 
these difficulties, so that a remarkably uniform product 
is obtained, the percentage of zinc oxid being small indeed. 

We have here an excellent example, as has been stated 
under another chapter, of a pigment containing 70 per 
cent barium sulphate, which may be regarded as perfectly 
pure and normal, and yet twenty-five years ago any pig- 
ment containing far 
less barium sulphate 
than lithopone 
would have been re- 
garded as adulter- 
ated. No man can 
reasonably state 
that barium - sul- 
phate is an adulter- 
ant to lithopone, 
for the obvious 
reason that it is a 
constituent part of 


the pigment. IGP Tee te ie ae - 
Lithopone has No. 23. LitHoPpoNE — Ground in Oil x510. 





gone through many vicissitudes; no pigment has been 
blackguarded quite as much as this, and yet no pigment 
has survived its condemnation as well as this. Almost 
every paint manufacturer in the United States finds some 
excellent use for it. Within the last seven or eight years 
lithopone has come into its own, and today there is no 
paint manufacturer in the United States, to the best of 
the author’s knowledge, who does not use this material. 
Ten years ago very few paint manufacturers used it at all. 

Since 1906 many chemists, including such capable 
men as Professor Ostwald, have attempted to find the 


44 CHEMISTRY AND TECHNOLOGY OF PAINTS 


cause of the darkening of lithopone in sunlight. When 
night comes a change takes place, and the following 
morning lithopone is as white as it ever was. ‘This 
property is called the “photogenic” quality. This photo- 
genic action goes on continually, and there have been 
a large number of investigators who have attempted to 
overcome this, and a review of the literature shows that 
most of the methods, with two or three exceptions, have 
been empirical. It has remained, however, for Professor 
W. D. Bancroft of Cornell University to delegate one of 
his students, W. J. O’Brien, to make these investigations, 
and the full account is recorded in Volume XIX of the 
Journal of Physical Chemistry, 113-44 (1915); an extract 
is herewith given of the phenomenon. 

That the darkening in sunlight is due to the formation 
of zinc from zinc sulphide was shown by the fact that 
the dark product reduced ferric alum, as shown by the 
appearance of a blue color with potassium ferricyanide, 
and that it is readily soluble in acetic acid, in alkalies, 
and in solutions of sodium chloride and sodium sulphate. 
The zinc is a direct product of the action of light on zinc 
sulphide. The results of the investigation are summarized 
as follows: Quenching in water prevents further oxidation 
of the red-hot zinc sulphide. It also disintegrates the 
semi-fused mass and dissolves out most of the soluble 
salts. Heating the barium sulphate-zinc sulphide pre- 
cipitate is necessary to dehydrate the zinc sulphide and 
to change its physical condition, so that it forms a dense 
mass with good body which can be ground more readily. 
The yellow color produced on overheating is due to an 
oxid film, as was shown by Farnau. The darkening 
of lithopone is not due to impurities such as iron, lead, 
cadmium, etc. The presence of salts which form soluble 
zinc salts, such as sodium chloride, sodium sulphate, etc., 


WHITE PIGMENTS 45 


accelerates the darkening of the lithopone. These salts 
dissolve away the zinc oxid film. This is similar to the 
behavior of magnesium in water. Magnesium does not 
decompose water very readily at ordinary temperatures. 
In the presence of magnesium chloride, however, the 
action takes place vigorously. The presence of salts which 
form insoluble zinc salts, such as the alkaline phosphates, 
bicarbonates, ferrocyanides, and borates, retards or pre- 
vents the darkening of lithopone. The action of light on 
the zinc sulphide is a reducing one, hydrogen sulphide 
and metallic zinc being formed. The reaction is not a 
reversible one; the metallic zinc formed is oxidized to zinc 
oxid; barium sulphate is not necessary for the darkening 
of the zinc sulphide. Heating the zinc sulphide is not 
necessary to get it to darken, although heating makes the 
zinc sulphide more sensitive to light, probably because 
the reducing atmosphere and the sodium chloride used 
remove the zinc film more readily. The zinc oxid film 
can be removed by boiling in a concentrated solution of 
zinc chloride. The zinc sulphide so treated will darken 
in the presence of a reducing agent. When barium sul- 
phate is precipitated with the zinc sulphide, it aids the 
darkening, due to the fact that it adsorbs the zinc sulphide, 
thereby giving increased surface exposure of the zinc 
sulphide. It probably also adsorbs the metallic zinc. 
The zinc sulphide will darken without the presence of a 
reducing agent if it is precipitated with barium sulphide 
and boiled in a concentrated solution of zinc chloride. The 
barium sulphate probably adsorbs metallic zinc as well 
as zinc sulphide, thus making the latter sensitive to light. 
The patented processes for the prevention of the darkening 
of lithopone depend upon the formation of an insoluble 
film around the zinc sulphide. It is impossible to make 
a lithopone that will not darken unless there is a film 


46 CHEMISTRY AND TECHNOLOGY, OF PATA 


protection of some kind over the zinc sulphide. A litho- 
pone of good quality that would not darken was made by 
producing an oxid film on the zinc sulphide and keeping 
the oxid content above 3 per cent and below 5 per cent. 
Aluminium oxid can be substituted for the zinc oxid. 
A film of sulphur protects to some extent; no experiments 
were made to determine the maximum efficiency possible. 

From the above we can readily see that the theory is 
a tenable one, and that the action of light on zinc sulphide 
is a reducing one, sulphuretted hydrogen and metallic 
zinc being formed. Metallic zinc is again converted into 
zinc oxid, and the color of the metallic zinc mixed with 
the other bases gives the gray shade that is apparent. 
The manufacture of a lithopone, therefore, that would 
not darken, by producing an oxid film and keeping the 
oxid content above 3 and below 5 per cent, would have its 
disadvantages, for in a rosin varnish or an acid resin 
varnish livering would eventually take place, and one of 
the principal features of lithopone has been that an acid 
resin or rosin varnish could be used and no chemical re- 
action would take place. 

The large use of lithopone today is for flat wall paints, 
for it can be mixed with the China wood oil-rosin var- 
nishes without the danger of livering or hardening, and 
it has every advantage as far as hiding power and freedom 
from mechanical defects that white lead and zinc oxid 
have, with the added advantage of being non-poisonous 
(although the danger of using a poisonous material on a 
wall is largely overestimated). Lithopone is likewise 
very largely used in the cheaper grades of enamel paints. 

As an interior white, a first coat white, or as a pigment 
in the lighter shades for floor paints, lithopone cannot be 
excelled for its body, durability, hardness, fineness of 
grain, and ease of application. It does not oxidize pro- 


WHITE PIGMENTS 47 


gressively, and this single feature has made it invaluable 
to the table oilcloth and floor oilcloth industry throughout 
the world. Its indiscriminate use, however, is not to be 
recommended, and the paint chemist should be permitted 
to decide when its value is the greatest. As a marine 
interior paint, either as a first coat or for making neutral 
paints where other whites would be necessary, it is found 
to outlast both zinc oxid and lead carbonate. 


Since the foregoing chapters were written, nearly ten 
years ago, there has been a very great improvement in the 
manufacture of lithopone, and nearly all the manufacturers 
today are making lithopone which is absolutely light-proof 
and some are making lithopone which contains as little 
as 4 of 1 per cent of zinc oxid or zinc hydroxid. 

Zinc oxid finds its way into lithopone when the barium 
sulphate is overreduced to barium oxide, or air comes 
in contact with the reducing mass either during or just 
before the final reduction. This is most evident when an 
analysis of barium sulphide is made, and the barium and 
the sulphur do not check together, the barium being 
slightly higher than the theoretical amount necessary for 
combination. This indicates that barium oxid is present 
in the barium sulphide. 

The manufacture of light-proof lithopone is by no 
means simple, because it depends more than anything 
else upon the purity of materials, particularly that of the 
zinc sulphate. 

The testing of lithopone for its light-proof quality can 
best be done by means of the ultra-violet light, and where 
a Wood screen is inserted, the non-lightproof lithopone in 
its dry state will fluoresce brilliantly. It is sometimes 
possible to determine the origin of the sample depending 


48 CHEMISTRY "AND “TECHNOLOGY OF FAinae 


upon the color of the fluorescence. Even in comparatively 
stable lithopone any particles of zinc oxid or zinc hydroxid 
will show up as brilliant white specks. 

Lithopone should also be tested for its light-proof 
qualities in dry state or in oil, and always in a watch glass 
in which the lithopone has been moistened with water. 
Blackening or darkening will sometimes begin in a few 
seconds, and if the lithopone is really light-proof. a five 
minute test is ample. 


TITANIUM WHITE 
Formula 25%. TiOs + 75% BaSO, 
Syn: elitanox 


The value of titanium dioxid as a pigment of great 
opacity and chemical stability has long been known, but 
its industrial production on a large scale, and its exploita- 
tion as a paint pigment were not placed on a successful 
basis until t919, when companies in Norway and the 
United States put it on the market in regular production 
after years of research. 

Titanium occurs abundantly in many parts of the 
world, in such ores as rutile, anatase, and brookite, and it 
forms the chief constituent of ilmenite which has been 
variously described as a combination with oxid of iron 
with the formula Fe(Mg)TiO; + 10 Fe.O3; and as a ferrous 
titanate with little or no actual Fe,O;. The present method 
of production consists of first freeing the crude ore, prin- 
cipally ilmenite, from as much of its impurities as is possible 
by mechanical means, pulverizing it, and mixing with con- 
centrated sulphuric acid to a thick paste. On heating this, 
a violent exothermic reaction takes place, and the resulting 
mass which contains sulphate of iron and titanium is ex- 
tracted with water. When the solution is heated nearly 
to boiling, the titanium sulphate, an unstable compound is 


WHITE PIGMENTS 49 


hydrolized to insoluble basic titanium sulphate which pre- 
cipitates in a very finely divided form. This precipitate is 
then washed by decantation, and in the form of a pulp, 
roasted in a rotary kiln where it becomes titanium oxid. 
Precautions must be taken throughout the process to keep 
the material in the proper physical condition so that it 
may be finally ground into 
a product having the best 
pigment properties. 

It has been found that 
a mixture of 25 per cent 
titanium dioxid and 75 per 
cent precipitated barium 
sulphate gives the best 
results as an all-around 
pigment. The barium sul- 
phate is added by suspend- 
ing it in the solution from 
which the basic titanium 
sulphate is precipitated 
and it is an integral part 
of the pigment. It is by no means an adulterant. Some 
processes call for the precipitation of BaSQ, on the TiQ, 
as it is made, the disadvantage in this case being the 
large iron contamination in the resulting precipitate. 

One of the principal obstacles the manufacturers had to 
contend with during the development of titanium white, 
was the yellowish cast of their final product, which, at the 
time, was generally considered as being due to the small 
amount of iron remaining as an impurity. It was eventually 
concluded, however, by some manufacturers, that this con- 
dition was caused by molecular change during the calcina- 
tion, for by excessive calcination, yellowish crystals of 
rutile could be produced. After an enormous amount of 





No. 24. TITANOX X700. 


50 CHEMISTRY AND TECHNOLOGY (OF - PATA ES 


research, it was found, that if a small proportion of the 
titanium was present in the form of phosphate, this change 
did not take place. 

Titanium white as produced at present is a pure white 
pigment having great hiding power or opacity, and is prac- 
tically inert to the usual paint and varnish vehicles. 

It may be used in varnishes that would react with zinc 
oxid, and it has a high resistance to acid and alkaline 
fumes. The judicious mixing of this material with zinc or 
lead produces satisfactory paints. It has been found that 
when used alone, the paint films are generally too soft, but 
when 20 to 30 per cent zinc oxid is added, a white paint of 
exceptional durability is obtained. 

For tinted paints, 40 to 50 per cent of zinc oxid is recom- 
mended. ‘Titanium white is made under the trade name 
Oleaelitanex,. ; 

As a pigment for exterior purposes it cannot compare 
with lead or zinc as it chalks very badly, and even chalks 
to a considerable extent when blended with zinc, lead, 
Blanc Fixe or other pigments. For making enamels for 
interior use it has excellent qualities, and is greatly im- 
proved when ground with about ro per cent of Asbestine. 

It is very likely that Titanox will be continually im- 
proved so that eventually formulas will be devised whereby 
it will find considerable advantage as an exterior paint. 


ANTIMONY OXID 


Trade name ‘‘Timonox” 


The development of this material as a paint pigment 
has been similar to that of titanium oxid. It is produced 
commercially in England under the trade name of Timonox 
by the roasting of metallic antimony and its sulphide ores. 
Two grades are on the market, the “Red Star” being the 


WHITE PIGMENTS 51 


-whiter and the “Green Star’’ being finer in texture, but of 
a pale ivory tint. Its physical properties are similar to 
those of titanium oxid and similar claims are made for it. 





No. 25. WHITE ANTIMONY OXID X315. 


Timonox is supposed to be immune to sulphur fumes, 
but this is not correct as it turns reddish-yellow (sometimes 
brownish-yellow if it contains a trace of iron) when sub- 
jected to sulphur gases. 


CHAPTER Ti 


THE OxIps OF LEAD 


THE oxids of lead used in making mixed paints are 
principally litharge, which is PbO, and red lead or orange 
mineral, Pb;QOu,. 

LITHARGE 


Chemical Formula, PbO; Specific Gravity, 9.2 to 9.5 


Litharge is the first oxid of lead; that is to say, when 
lead is melted and heated in a current of air the first oxid 
produced is the PbO, yellow in color, and known as 
litharge. Very pure litharge has the color of pale ochre. 

Litharge in the manufacture of preservative paints 
has excellent protective qualities, because it is basic and 
resists corrosion. Furthermore, litharge and linseed cil 
make a very hard cementitious film which withstands 
abrasion, but unfortunately litharge combines with lin- 
seed oil so rapidly that when used in mixed paints to 
any great extent it tends to “liver” and saponify. On - 
the other hand, a number of black paints which are 
composed of lampblack, carbon black, charcoal, or a mix- 
ture of these, are held together by the use of litharge, and 
where these paints are used within a month or two after 
they are made they serve their purpose perfectly. 

Litharge is soluble in acetic acid, and the other 
impurities in it are generally insoluble, so that a very 
rapid test can be made from the paint manufacturer’s 
point of view by simply boiling in acetic acid. Litharge 
varies in texture under the microscope, as is shown in 
the accompanying photomicrographs. 

52 


THE OXIDS OF LEAD 53 


Flake litharge is generally used by varnish makers or 
oil boilers for making drying oil, but the more finely 
powdered forms of litharge have a peculiar construction, 
and when the litharge is impure and contains metallic 
lead and red lead it is distinctly noticeable under the 
microscope. 


Rep LEAD 


Chemical Formula, Pb;0,; Specific Gravity, 9.0 


Red lead is a very heavy orange-red pigment, more or 
less crystalline in structure. It is prepared by heating 
litharge to a temperature of 600° to 700° F. 

Owing to the conditions 
under which it is made it 
contains from a trace to 
an appreciable percentage 
of litharge (PbO), and 
when used for paint pur- 
poses it cannot be said 
that-a small content of 
litharge does any harm. 
When prepared in linseed 
oil it must be freshly used, 
No. 26. RED Lrap—Photomicrograph otherwise NM forms ae dis- 

X00. tinct combination with lin- 
seed oil and becomes hard and unfit for use. In its 
physical characteristics it can be compared with plaster 
of paris. It acts very much like plaster of paris when 
mixed with water. Once set, it may be reground and will 
never set again. Its use as a priming coat for structural 
steel has been enormous, but engineers who have studied 
the subject have come to the conclusion that there are 
other materials just as good, or better, which are easier 
to apply and do not possess the characteristic difficulties 





54 CHEMISTRY AND TECHNOLOGY OF PAIN aS 


of application. The author has made many investigatioris 
on this subject, and for further detail would refer the reader 
to the Journal of the Society of Chemical Industry, 
Vol. XXI, January, 1902, and Vol. XXIV, May, 1905. 

There are some manufacturers in the United States. 
who make red lead from litharge and use nitrite of soda 
as an oxidizing material, and in the manufacture of this 
type of red lead carelessness in manufacture will result 
in a fairly large percentage of caustic soda remaining in 
the red lead. Caustic soda finds its way frequently into 
litharge when it is made 
by what is known as the 
nitrate process, in which 
nitrate of soda and me- 
tallic lead are fused to- 
gether, yielding an oxid of 
lead; PbO} andeniitiice on 
soda, NaNO,.! Red lead 
manufactured by this pro- 
cess will usually contain a 
small amount of caustic 
soda and nitrite of soda, 
ANG seSuCchoered — 1eAc. eecls 
though otherwise pure, makes a very poor paint, because 
the caustic soda saponifies the linseed oil, and exposure 
to weather of a few months will turn the red lead white 
or pinkish white and make it very soluble in rain water. 
Rust is also rapidly produced under such red lead, and 
therefore in specifying red lead it is well for the engi- 
neer to insert a clause that an aqueous mixture of red 
lead shall show no reaction with phenolphthalein. 

Within the last five years a great improvement has 
been made in the manufacture of red lead, and this 





No. 27. LIrHARGE—Photomicrograph X<300. 


1 See Holly’s “Analysis of Paint and Varnish,” p. 221. 


THE OXIDS OF LEAD 55 


improved form has been known as Dutch Boy Red Lead, 
which is practically a chemically pure Pb;O,. Pure red 
lead was the one material which had never been sold either 
ground in oil or ready for use, owing to the fact that the 
large content of litharge combined with the fatty acid 
of the oil and the glycerine and formed a lead soap. It 
is well known that litharge cement, used for many pur- 
poses around a factory, is litharge and glycerine, which 
sets up hard within an hour and forms a vitreous product. 
It is also well known that when linseed oil is neutralized 
with caustic soda, and the resulting linoleate of soda 
soap filtered out, a ready mixed or semi-paste red lead 
can be made which will remain soft for many months, 
but the proprietary brand of red lead just referred to 
manufactured by the National Lead Company, is a pure 
red lead similar in composition to orange mineral, which 
remains soft and produces a paint that has many advan- 
tages over the old-fashioned red lead. 

Many engineers and shipbuilders prefer to use dry 
red lead, and a proper specification for dry red lead 
should be one that will contain the minimum amount 
of litharge. : 

It cannot be denied that red lead is one of the best 
priming materials that we have, but under no circum- 
stances should less than 28 lbs. of dry red lead be mixed 
with one gallon of linseed oil. Many of the bad effects 
and failures of red lead are not due to the lead itself, 
but to bad application and insufficient dry materials. 
As a matter of fact, the best results with red lead are 
obtained (in the author’s experience) by using 33 lbs. 
and one gallon of linseed oil. To this oil may be added 
one half pint of any good Japan drier. 

As a priming coat red lead possesses excellent pre- 
servative qualities, providing it be properly applied within 


56 CHEMISTRY AND TECHNOLOGY OF PAINTS 


a reasonable time. If red lead be used in the proportion 
of 17 lbs. to one gallon of linseed oil it forms a very poor 
coating on account of the separation of the pigment 
from the cil, particularly on a vertical surface. In a 
pamphlet published by a manufacturer a large number of 
precautions were given to the consumer for the prepara- 
tion of red lead as a priming coat, the neglect of any 
one of which might produce failure for the paint. As a 
prominent engineer remarked, he did not care to specify 
a paint in which there 
were seventeen chances 
of its failure due to a’ 
possible fallibility of hu- 
man nature. The use of 
a dry pigment mixed with 
oil and applied within one 
hour of its mixture is con- 
trary to the progress of 
the present day, when 
paints finely ground by 
machinery eee taking the No. 28. FRENCH ORANGE MINERAL — 
place of all others. A dry Photomicrograph X250, not very uni- 
pigment stirred by hand ‘0m ™ stn. 

in a pail of oil carries with it a large number of air 
bubbles which become encysted and carry oxygen 
and other gases to the surface to be protected. The 
engineer should, therefore, not specify that a paint be 
made entirely of red lead and linseed oil and sent ready 
for use to the place of application when such specifica- 
tions cannot be reasonably executed. On the other 
hand, where red lead is specified the engineer or paint 
manufacturer who can supply a material containing 
between 4o and 50 per cent red lead and 50 and 60 
per cent inert base is delivering a far better article, 





THE OXI DSO LEAD 57 


which can be more easily applied than the undiluted red 
lead alone. 

The author made a large number of experiments on 
red lead mixed with linseed oil containing a small per- 
centage of drier, applying these mixtures to steel. The 
mixture was first applied the moment it was thinned, and 
then at short intervals, up to the moment the red lead 
began to combine with linseed cil so as to make it 
impossible to handle the brush. The results of the experi- 
ment showed that freshly 
applied red lead was not 
as good as it was if applied 
one hour after it was mixed. 
The paint with which these 
experiments were made con- 
tained 24 lbs. red lead to 
one gallon of paint, which is 
approximately equal to 33 
Ibse, ary. red. leat. to,,one 
gallon of oil. The difficulty 
No. 29. RED LrAp — Photomicrograph in handling paint of this 

x200 of paint film freshly applied, kind is very pred t owing 
showing separation of the pigment to the excessive weight of 
from the oil. ; ‘ ; 
the paint as carried by the 
brush. Structural iron painters all complain that muscular 
fatigue ensues where undiluted red lead is used, and when 
the inspector is not watching they will surreptitiously 
add an excessive quantity of oil, or volatile thinner, 
in order to lighten their labor, and for this reason red 
lead has frequently failed, when as a matter of fact it 
would have proved a perfect success had the original 
specifications been adhered to. On the other hand, there 
should be no need of using a protective paint involving 
such great difficulties when there are dozens of others 





58 CHEMISTRY AND TECHNOLOGY OF PAINTS 


that are as good, not only from the standpoint of pro- 
tective influence but also on account of the ease of 
mechanical application. 

It has been mentioned by many writers that one of the 
serious defects of red lead is the ease with which it is 
attacked by sulphur gases, but this objection does not 
hold good where it is properly and quickly coated over 
with a protective coat of the bituminous class. That 
red lead in its pure or concentrated state is not as good 
as a paint containing a solid 
diluent has been shown time 
and again where silica, 
lampblack, graphite, silicate 
of alumina, and such lighter 
pigments were mixed with 
it. Its extraordinarily high 
specific gravity is very much 
against its use as a paint, 
but if a mixture of one 
pound red lead and one 
pound wood black is taken No. 30. Rep LEAD — Photomicrograph 
the average specific gravity 150, applied one hour after mixing, 
of the two is equal to that showing separation and air bells en- 

‘ q 2 cysted in film. 
of zinc oxid. Its spreading 
and lasting power is increased, so that a mixture of 
this kind is equal to a mixture of any of the good pre- 
pared paints for structural steel. Two large exposure 
tests made by the author in 1899 and examined in 1905 
showed that a mixture of 50 per cent red lead and 
50 per cent graphite ground fine and mixed in a pure 
Imseed oil containing 5 per cent of lead drier wore almost 
as well as a mixture of 75 per cent Fe,O; (ferric oxid), 
20 per cent silica, and 5 per cent calcium carbonate. 
The former paint, when the hand was rubbed over it, 





THE OXIDS OF LEAD 59 


showed slightly more destruction of the oil, the graphite 
giving a stove polish effect on the hand. The latter 
paint also showed a very slight stain on the hand, but not 
quite as marked as the former. The metal underneath 
both was in a good state of preservation, three coats of 
paint having been applied. The exposure was made 
on a slanting roof in New York City. 

Red lead has had the great advantage of having been 
the first protective paint ever used, for years no better 
paint being known. In this respect it is analogous to 
white lead. Much of the good reputation of white lead 
is due to the fact that for centuries there was no other 
white paint, consequently no comparison could be made. 
It must be borne in mind that all these experimental 
researches concerning red lead are based on very fine red 
lead, and no consideration is given to the detrimental 
reports concerning red lead due to the fact that it was 
improperly made and coarse. : 

A laboratory test of red lead always shows up remark- 
ably well. A steel saucer painted with red lead in the 
laboratory will demonstrate that this pigment is superior 
to many others, but a field test of material made accord- 
ing to a laboratory formula and applied on several tons 
of steel will generally show the opposite, for the obvious 
reason that in the laboratory a small test is usually 
carefully applied and little exertion is necessary, either 
with the mixing of material or for its application. The 
temperature conditions of the laboratory being normal, 
the person who mixes the paint usually scrutinizes the 
result carefully. On the other hand, in the field or at 
the shop a-brush is used which will do the greatest 
amount of covering with the least amount of exertion. 
The mixture may not be made by the best possible for- 
mula, and, if it is, more thinning material is generally 


60 CHEMISTRY AND TECHNOLOGY OF PAINTS 


added until it works freely. The vertical part of the 
surface will, on account of its position, be more difficult 
to cover, and the paint will sag or run from it; whereas, 
the flat plate or saucer-shaped cup used in the laboratory 
holds the material in place by virtue of its position. 


At the present time, red lead is totally different as a 
steel protective paint as compared with the dry red lead 
of a decade ago. Improvements in its manufacture have 
led to the perfection of red lead ground in oil, so that it 
will not thicken or liver. In the United States a red 
lead has been marketed under the name of “Dutch Boy 
Red Lead in Oil,” which can be reduced with linseed oil 
and drier, and is far superior to the old-fashioned dry red 
lead mixed on the job. It is a most excellent paint, and 
when coated over with a waterproof paint gives immunity 
from rust. 


In the sublimation of Galena a peculiar sulphide of 
lead is produced, which has been known commercially 
as blue lead, on account of its blue-gray appearance. 
This product has been on the market for several years. 
The contention is that sulphur fumes do not affect it as 
they affect red lead. As a priming coat it has been well 
spoken of. Its composition 1s as follows: 





CatDOlines qten eames B26 a ae ieee 
Lead Sulphate...... 52°02. 5 7 en 49.79 
Lead Sulphite as 20504. che ee 1.44 
Lead Sulphtigeaieess Ai RSW. a 4.93 
Lead*Oxid hee 29048 i. 6 AI. 34 
Zine. Oxid See eee 2945 2k ae T.00 

100. Or 100,22 


No truly representative analysis of this material can 
be given, owing to the variation in the amount of sul- 
phate, sulphite, and sulphide. The material is not very 


THE OXIDS OF LEAD 61 


fine; in fact, it contains an appreciable amount of grit, 
which, however, is removed in the second grinding. 

The pigment is not permanent to light, but in all 
probability this change in its tone is due to a chemical 
rather than to a physical decomposition. 


CHAPTER IV 


THE INORGANIC RED PIGMENTS 


THE red pigments used in the manufacture of mixed 
paints are principally the oxids of iron, the red oxids 
of lead, and the permanent vermilions. No space will 
be devoted to the sulphide of mercury (quicksilver ver- 
milions), as the use of these materials has been super- 
seded entirely by aniline or para-nitraniline vermilion. 
Likewise no attention will be paid to the sulphide of an- 
timony reds, as they are obsolete in paint manufacturing. 

Among all the red pigments in the paint industry 
the oxids of iron take the lead as by far the most useful. 
Several years ago the author called attention to the fact 
that various forms of ferric oxid having the formula 
Fe,0; could be used as rubber pigments. The sulphur 
used in the vulcanizing of rubber had no effect on the 
ferric oxid, no sulphide of iron being formed in the com- 
bination. On investigation it was found that some forms 
of ferric oxid are remarkably stable in composition, acting 
in many regards like a spinel. Exhaustive tests made 
with some of the ferric oxids used as paints for the pro- 
tection of steel and iron shcw that they are far superior 
to red lead and to graphite as paint protectives, being 
midway between the two in specific gravity. A mixture 
of graphite and ferric oxid (containing 75 per cent Fe,O; 
and 25 per cent silica) outlasted graphite by two years 
and red lead by three years. These tests were made on 


horizontal roofs, and eliminating the question of the cost 
62 


THE INORGANIC RED PIGMENTS 63 


of the paints, the ferric oxid stood the test and was the 
cheapest in the end. No argument can be adduced that 
ferric oxid is a carrier of oxygen, for it is a complete 
chemical compound, is not readily acted upon by dilute 
acids, not affected by alkalis nor by sulphur gases, and 
as a paint the author has not been able to demonstrate 
that it reacts on linseed oil. 

All of these arguments refer, of course, to a ferric 
oxid of known purity and definite composition either as 
pure Fe.O; or as Fe.O; containing 25 per cent of silica. 
In the course of its manufacture from the waste products 
of wire mills, for instance, or direct from ferrous sulphate, 
the processes being analogous, there is a likelihood that 
a small percentage of free sulphuric acid may cling 
mechanically to the substance. A good sample boiled 
with water and tested with methyl orange will demon- 
Bitate tnis detect. It is wise, therefore, under all: cir- 
cumstances to add up to 5 per cent calcium carbonate 
in any or all of these ferric oxid paints. There is, how- 
ever, another ferric oxid made from. Persian ore. Over 
one hundred analyses of this ore in the laboratory of the 
author have shown that its composition will not vary 
‘more than 2 per cent either way, it being 75 per cent 
_ Fe,O; and 25 per cent SiOx. 


VENETIAN .REDS 


Venetian reds have sometimes been described as burnt 
ochres, but this definition of the Venetian reds is incor- 
rect. The generally accepted composition of the Venetian 
red is a combination of ferric oxid and calcium sulphate, 
in which the ferric oxid will run from 20 to 4o per cent, 
and the calcium sulphate from 60 to 80 per cent. When 
ferrous sulphate is heated with lime an interchange or 


64 CHEMISTRY AND TECHNOLOGY OF PAINTS 


reaction takes place, the sulphuric acid of the copperas 
going to the lime while an oxidation of the iron takes 
place. Another method known as the wet method is 
the direct reaction between ferrous sulphate and wet 
slacked lime. 

Venetian red has been known as a paint pigment for 
upwards of a century, and while theory would indicate 
that it is by no means as desirable a pigment to use as 
other mixtures of ferric oxid, it must be apparent that 

: in view of the fact that it 

Lf. i has given general satisfac- 
gf | tion it is by no means as 
— desirable a pigment 
ae undesira pig as 
| ‘ ,, , chemists indicate. The ten- 
& * dency, however, at the 
' present time is for manu- 
: 5 J s / facturers to buy ‘strong 
Ne So purre._oxids “and™ Yeduce 
~~ : : — Co them with other inert 

ee fillers, for the principal 
No. 31. ENcLisH VENETIAN Rep— reason that a Venetian red 

Photomicrograph 250, showing cal- carrying a high percentage 
cium sulphate crystals. : 
of calcium sulphate and an 
unknown quantity of water or moisture tends to become 
hard in the package, whereas the mixtures of known 
composition remain soft for many years. Venetian reds 
are all of the familiar brick color shade, the color of 
bricks being caused by the same pigment as the one that 
gives the color to Venetian red. 





- 


INDIAN RED 


This is supposed to have been named by Benjamin 
West, a-celebrated American artist who lived more than 
a century ago, and who as a boy used a few primary 


THE INORGANIC RED PIGMENTS 65 


earth colors as pigments for paint. One of these was a 
natural hematite, and he observed that the Indians used 
this for painting their faces. The name is also supposed 
to have had its origin in the fact that “‘Persian’ Gulf 
Ore,’ which was found in the Orient, was exported to 
England under the name of ‘‘East Indian Red.” This 
Persian Gulf Ore is likewise a hematite, and later on a 
similar ore was found in parts of England which, when 
mined, looked very much like coal, but when crushed and 
ground in water turned 
a deep blood-red. The 
old name for this mineral 
is still ‘“‘blood-stone,”’ and 
some very fine specimens 
of this mineral are still 
mined in England in con- 
junction with beautiful 
quartz crystals, so that 
we find in England a care- 
ful selection. ; 
The native Indian red No. 32. AMERICAN VENETIAN RED— 
will run go per cent Fe.Os, Photomicrograph 250, showing fine 
: grains of calcium sulphate. 
the American 88 per cent, 
and the Persian 75 per cent, the balance in every case 
being silica. The Indian red of commerce, however, is 
an artificial product made like the base of the Venetian 
red by calcining copperas and selecting the product as 
to shade. There is no pigment, with possibly the excep- 
tion of lithopone and artificial barium sulphate, which will 
approach Indian red in fineness of grain. The prices 
which a fine, pure Indian red or ferric oxid of any shade 
will command are most remarkable, many tons being sold 
every year in large quantities at as high a price as fifty 
cents per pound and used entirely for polishing gold, 





66 CHEMISTRY AND TECHNOLOGY OF PAINTS 


silver, and other metals. 
The well-known “‘ watch-case 
rouge” is nothing but pure 
eN Indian red which has been 
* ground, washed, and treated 
Bie eee af es mechanically with so much 
Ligue? ite,, Tee <7 = % care that three- -quarters of 





ty oe he . / its selling price is represented 
Wt ee 

ee ie vy in the labor of manipulation. 
Ne ge - eS cs a8 pao . ; 
“et... 8» sii, therefore, fine ferric oxid 


NRG ae & be mixed with linseed oil it 

No. 33. AMERICAN HEMATITE — Photo- can be easily seen from the 

micrograph x250, showing a few large nature of the physical char- 

reac acteristics of the pigment 
that a remarkably good result is obtained. 


CHAPTER V 
THE YELLOW PIGMENTS 


THE yellow pigments are the ochres, the raw siennas, 
chrome yellow, and the chromates. 

The ochres are all rust-stained clay, and both the 
French and the American contain approximately 20 per 
cent of rust or ferric hydroxid and the balance clay. 

The raw siennas differ from the ochres in that the 
amount of hydrated oxid of iron is often in excess of 
that of clay, and the nature of the pigment is such that 
when finely ground it is a stain and not a paint. 

The chrome yellows are all lead chromate variously 
precipitated and of varying composition, depending upon 
the shade. 

The other chromates, such as zinc chromate and 
barium chromate, have come into use in paints within 
the last ten years, owing to their alleged property of 
preventing corrosion. 


AMERICAN YELLOW OCHRE 


There are large quantities of ochre found in the 
United States, but principally in Pennsylvania and in 
Georgia. There are, of course, a great many other 
deposits, but for the paint industry these are the prin- 
cipal sources. American ochre ranges in composition 
from ro to 30 per cent of ferric hydroxid, the balance in 
either case being clay, and on this point it is well to note 
that ochre and sienna have the same composition, except- 


ing that there is generally a reversal in the percentages 
67 


68 CHEMISTRY AND TECHNOLOGY OF PAINTS 


of clay and oxid of iron. Some ochres found in America 
are finer than those imported from France, although 
French ochres as a general rule are decidedly more 
brilliant in color. 

In the trade there are many other ochres, which are 
sold under the name of cream ochre, gray ochre, white 
ochre, and golden ochre, all of which are clays containing 
either carbonaceous matter 
or iron rust, for, after all, 
ochre is simply clay stained 
with rust. 

Cream ochre contains 
as low as 5 per cent of 
iron rust or ferric hydroxid, 
the balance being silica 
and clay. It has very little 
hiding power, and is con- 
sidered of very little value 
aS a primer on wood, for 





No. 34. ORDINARY AMERICAN WASHED 
which it is used to quite OcHRE — Photomicrograph x250, pow- 


dered and bolted; lower in iron than 


a lar Se extent. the French, but of uniform grain. 


Gray ochre is silica, 
clay, and carbonaceous coloring matter, or is colored 
with a trace of ferrous hydroxid or greenish rust. It is 
used as a filler, or for a cheap paint. 

White ochre is nothing more or less than clay, and 
has no value whatever as a paint material. 

Golden ochre is either French ochre or American 
ochre which is brightened with some chrome yellow. 
There are various shades of golden ochre sold, depending 
upon the shade of chrome yellow with which it is mixed. 
Some of them are perfectly orange colored, and contain 
as high as 12 to 15 per cent of chemically pure orange 
chrome yellow. 


THE YVELLOW PIGMENTS 69 


Green ochre is similar in composition to gray ochre, 
excepting that it contains a larger percentage of ferrous 
hydroxid. It is principally found in Bohemia under 
the name of terre verte. It has little or no hiding power 
of itself, but is very largely used as a base for cheap 
lakes on account of its 
adsorbent quality for cer- 
tain aniline colors. 

Yellow oxid is a syn- 
onym for raw sienna, and 
is practically the same 
thing. A typical analysis 
of yellow oxid will show 
hydrated oxid of iron 70 
per cent and clay 30 per 
cent, 

No. 35. AMERICAN WasHED OCHRE — For the benefit of the 
Photomicrograph X250, of the same chemist it must be stated 
composition as French ochre. 

that when analyses are 
not given and small percentages of lime and magnesia 
are found, it is understood that these are natural con- 
comitants of ochrey earths. 





FRENCH YELLOW OCHRE 


French yellow ochre has been used in America for 
many years, and is analogous in composition to American 
ochre; but as a general rule the French ochres are more 
brilliant in shade. Nearly all of the French ochres which 
are imported into the United States have a composition 
of about 20 per cent of hydrated oxid of iron and 80 per 
cent of clay, and one of the most popular brands has 
for years been known as J. F. L. S. These letters stand 
for “‘Jaune, Foncé, Lavé, Surfin,’ which mean, “Yellow, 
Dark, Washed, Superfine.” These, letters are varied 


70 CHEMISTRY AND TECHNOLOGY OF PAINTS 


according to the treatment that the ochre gets, but the 
J. F. L. S. is the most popular. 7 

In color, the French ochres are more brilliant, as has 
been stated, but the American ochres are invariably 
finer; but this, of course, refers only to the American 
grades of equal price. 


RAW SIENNA 


Raw sienna differs from ochre inasmuch as ochre is 
80 per cent of clay colored red with 20 per cent of ferrous 
hydroxid. Sienna is al- 
most the reverse, and con- 
tains from 30 to 40 per cent 
of clay, and from 60 to 
, 70 per cent of ferrous hy- 
_ droxid. The optical differ- 
/ ence between sienna and 
ochre is, that sienna when 
finely ground in oil is trans- 
lucent and almost trans- 
a parent. Ochre is always 
No. 36. J. F. L. S. Ocurr— Photo. Opaque. Sienna is a very 

micrograph x250, showing crystalline durable color, and very per- 

ee manent, but must never be 
mixed with any of the organic lake pigments, for it de- 
stroys even the permanent lakes, and changes their bril- 
liancy to a muddy tone. 





CHROME YELLOW 


Chrome yellow is chromate of lead, made by mixing a 
solution of sodium dichromate with a lead solution, gener- 
ally lead acetate. The lead acetate is usually made by one 
of these three processes — 


THE YELLOW PIGMENTS 71 


t. Metallic lead in finely divided form is dissolved in 
acetic acid to saturation. 

2. Litharge is dissolved by boiling in acetic acid. 

3. Lead acetate is dissolved in water. 

By regulating the concentration of the solutions, the 
temperature, and by other manipulation, a wide variety 
of yellows are produced with various physical characteris- 
tics and ranging in shade from a very pale primrose to a 
deep orange. Alkali, usually in the form of sodium car- 
bonate (soda ash) is added to produce the deeper orange 
shades, and acid is added to produce the lighter shades. 
Being of high specific gravity they settle rapidly, and may 
be washed by decantation without trouble. Sometimes 
the nitrate of lead is used in place of the acetate. Sometimes 
the more expensive potassium dichromate replaces the 
sodium salt to produce clearer colors. 

All of the chrome yellows are perfectly permanent, 
provided they are thoroughly washed to free them from 
residual salts. Manufacturers are now abandoning the 
old mechanical method of stirring chrome yellow after 
it is precipitated, and are substituting air stirring, which 
avoids any possible tendency to produce lead sulphide, 
the air converting the sulphide into sulphite and sulphate. 
Chrome yellows when thoroughly washed are permanent 
to light, but they cannot be recommended where sulphur 
vapor is generated, owing to the formation of lead sul- 
phide, traces of which detract from the brilliancy of the 
color of the pigment. 


CHROMATE OF ZINC 


Chromate of zinc has only come into general use 
within the last ten years in mixed paints and paints 
generally, on account of its alleged rust-preventing prop- 
erties when used as a priming paint on steel. 


7B CHEMISTRY AND TECHNOLOGY OF PAINTS 


Chromate of zinc is made as follows: Zinc oxid is 
boiled in a solution of potassium bichromate for several 
hours and filtered and dried with slight washing; or a 
hot neutral solution of zinc sulphate is precipitated with 
potassium chromate. 

Chromate of zinc is soluble to a considerable extent 
in water, and therefore should not be used as a finishing 
coat, as rain will streak the surface. For example, a 
green paint made of chromate of zinc and blue shows 
yellow streaks when exposed to the weather. 

This material is used to some extent by artistic 
painters, and as oil paintings are never subjected to the 
elements it is under those circumstances a perfectly per- 
manent color. 

For interior painting and flat wall paints, chromate of 
zinc, therefore, has an advantage, as much more brilliant 
tones are obtained and much more delicate shades are 
obtained than with the chromate of lead. It has very 
little hiding power or opacity, and in tinctorial strength 
is much weaker than the chromate of lead. 

If contained in a mixed paint, when the pigment is 
thoroughly washed with benzine and freed from oil or 
medium, chromate of zinc can easily be recognized, be- 
cause the pigment when shaken with hot water in a test 
tube is invariably colored yellow. This, however, must 
be further verified, as barium chromate reacts the same 
way. 

YELLOW IRON OxIDs 

Yellow iron oxids are produced artificially by patented 
processes and are identical in properties with the manu- 
factured red oxids. They have become valuable pigments 
and are often used to replace ochres where brighter and 
stronger chemically inert yellows are required. They are 
sold under such trade names as “Ferrite” and ‘‘Ferrox.”’ 


THE YVELEOW PIGMENTS 73 


Chemically these colors are not oxids but consist of 
98-99 per cent Fe(OH); the impurities being mainly 
CaSQ,. 


CADMIUM YELLOW CdS 


Cadmium yellow is made by passing a current of hy- 
drogen sulphide through a solution of any cadmium salt. If 
the solution is made slightly acid, a yellow shade is pro- 
duced, and by changing the proportions of acid and adding 
ammonium sulphide, deeper shades may be made, up to the 
deepest orange. Change of temperature also affects the 
shade. A bright vermilion also exists. This is a cadmium 
selenide. 

Lithopone, zinc oxid and particularly zinc chromate, 
are frequently blended with cadmium sulphide in order to 
match certain shades. Cadmium sulphide is used under 
conditions where the cheaper bright yellows would fail, its 
main uses being, in the coloring of vulcanized rubber, as 
an artists’ color, and for switch and target enamels. It 
should under no circumstances be mixed with pigments or 
vehicles containing metallic salts or other substances that 
react with sulphur. ; 

Cadmium lithopone is a combination of cadmium sul- 
phide and barium sulphate. It is made the same way as 
regular lithopone, the reaction being BaS + CdSO,; = BaSO, 
+ Cds. 


ANTIMONY SULPHIDE Sb.S; 


Antimony sulphide is analagous to cadmium sulphide, and 
is used to some small extent as an artists’ color, and in the 
coloring of rubber, but for very little else. It is made in 
two shades, the golden or orange, and the scarlet or crimson. 

The golden or orange shade is made by the action of 
hydrochloric acid on potassium sulphantimonate and crim- 
son or scarlet antimony is made by precipitating a solution 


74 CHEMISTRY AND TECHNOLOGY OF PAINTS 


of an antimony salt, usually antimony chloride or tartar 
emetic with sodium thiosulphate. Antimony yellows fre- 
quently contain calcium sulphate and usually contain free 
sulphur. 

ARSENIC SULPHIDE As»S3 


The arsenic sulphides are similar to the antimony sul- 
phides and were largely used at one time. At present they 
are little used except as rubber colors. The yellow shade or 
king’s yellow (orpiment) is made from arsenic oxid in the 
same manner as golden antimony is made, and the orange 
shade or realgar, is made in the dry way by fusing sulphur 
and arsenic. Both are very poisonous and contain free 
sulphur. 


CHAPTER VI 
THE BROWN PIGMENTS 


THE principal brown pigments used in the manu- 
-acture of paint, excepting the aniline lakes, are the burnt 
siennas, the burnt umbers, burnt ochres, Prince’s Metallic 
or Princess Mineral brown and Vandyke brown. 

The siennas have practically the same composition as 
the ochres, except that they contain more iron and have 
a small percentage of manganese. The shade of raw 
sienna is much deeper than that of the darkest ochre, and 
burnt sienna is a very reddish, light brown. Generally ~ 
speaking, the finest siennas are mined in Italy. Burnt 
sienna is much more transparent than raw sienna. 

The umbers are similar in composition to the siennas, 
with the exception that they all contain manganese and 
are of a much deeper brown and do not approach the red. 

The Princess Mineral brown or Prince’s’ Metallic 
oxids are calcined carbonates, silicates, and oxids only 
found in America, and are very largely used, particularly 
for the painting of wood. 

Vandyke brown is a very deep brown, and is trans- 
lucent when finely ground, containing more than so per 
cent of organic matter. 


AMERICAN BURNT SIENNA 


This is a permanent reddish brown pigment made by 
calcining raw sienna, raw sienna being a hydrated oxid 
of iron containing clay. When burnt the percentage of 
Fe.O;, or ferric oxid, ranges from. 25 to 60 per cent, 

75 


76 CHEMISTRY AND TECHNOLOGY OF PAINTS 


depending upon the original ore. There is one grade 
found in the Pennsylvania section which assays as high 
as 80 per cent ferric oxid, and is known as double strength 
sienna. This is richer and deeper than the Italian sienna, 
and when reduced with ordinary clay and ground in oil 
makes a staining pigment equal to the Italian. From a 
raw-material standpoint the Italian siennas when tinted 
with 20 per cent of white show a bluish tint, whereas the 


6, American siennas show a 
LE Le a brownish or yellowish tint, 
GO Sra 
Z vote SO apy + and only one who has had 
Pe 9? wh 88 een 
| en Da ete 2 a 2 great deal of experience 
se ¢ *, s é ~~, We ee - 
He. Sontion £ * 3 4 in tinting out these siennas 
ee ee srs o Lt € * can tell empirically the dif- 
*. @& : ie ey ae . 
oe ae zt ference between an Ameri- 
ew pe / . : 
' Sy oe at So 7 can and an Italian sienna. 
ee. an * ‘. ye ' The Italian and the Ameri- 
to ! oe can slennas normally con- 
~ 7 cP a 
~~. “iyo tain some calcium salts, 


No. 37. AMERICAN Burnt SIENNA— but occasionally some ores 
Photomicrograph 250, excellent qual- are found which are free 
A ery Ss from lime compounds. For 

paint purposes, however, these are no better than those 
that contain lime, for many grinders add from 5 to to 
per cent of whiting to umbers and siennas to prevent 
them from running or disintegrating when used as stain- 
ing colors. | 


ITALIAN BuRNT SIENNA 


Italian burnt sienna is made from raw sienna, the 
raw sienna being a hydrated oxid of iron containing clay, 
in which the iron predominates, the burnt sienna being 
of the same composition minus combined water. The 
hydrated oxid of iron is normally yellow, and when 


THE BROWN PIGMENTS a9 


this is burnt the ferric oxid which is produced is reddish 
or reddish brown. 

Italian burnt sienna differs from most American 
burnt siennas in that its ferric oxid content is generally 
greater. The Italian burnt siennas average from 60 
per cent Fe,O; to as high as 75 per cent. The American 
burnt sienna, known as double strength sienna, which is 
equal in iron content to the Italian, differs totally in 
shade, the American being of the order of a Havana 
brown, the Italian being of a maroon type. 

Siennas in mixed paints are largely used for their 
tinting quality, the resulting shade being a yellowish 
maroon or salmon color of extreme permanence. After 
several years’ exposure a mixture of white and burnt 
sienna will darken slightly, but will never fade. 

Under the microscope a finely ground sienna shows 
little or no grain. 


Raw AND BURNT UMBER 


The chemical composition of the umbers differs slightly 
from that of the siennas, umbers having a larger man- 
ganese content. The best raw umber is mined and finished 
in Italy, and an inferior grade is produced in the United 
States. Both raw and burnt umbers produce shades and 
tints that cannot be duplicated by other colors of moderate 
cost. Burnt umber, like burnt sienna, is more reddish 
and transparent than the raw product. 

Burnt umber is a very useful pigment; it is made in 
the United States and also imported from Italy, Cyprus, 
and European Turkey. All umbers normally contain 
over 5 per cent of manganese dioxid, while some of them 
contain as high as 20 per cent manganese. The Turkey 
umbers are generally richer in manganese than the Ameri- 
can umbers. 


78 CHEMISTRY AND TECHNOLOGY OF PAINTS 


A typical analysis of burnt Turkey umber would be 
as follows: 





Calcium: Carbonatete 26 sec 0 7% 
Silica sl ea eee a ee 34% 
Manganese: Dioxid 22... ee 14% 
Ferric Oxid shoe ee 42% 
Alumina . \it/code Sees en 3% 

100% 


A typical analysis of an American burnt umber 
would be: 


Silica and-Alumina (clay) 7) eee 60% 
Ferric: Oxid ..¢ cate .o et ee ee IE 
Manganese Dioxid. 70.5... 0 8% 
Calcium Carbonate: soo nn 5%, 
Carbon and Carbonaceous matter........ 2% 

100% 


These types would indicate that an American umber 
is not as strong and does not contain as much ferric oxid 
and manganese dioxid as a Turkey umber. 


BURNT OCHRE 


Burnt ochre is distinctively an American color, and 
differs in physical quality from burnt sienna in so far as 
the burnt ochre has hiding power and the sienna has trans- 
lucent or staining power. Burnt ochre is more like a brown 
paint, and burnt sienna like a mahogany stain. Burnt 
ochre covers solidly; burnt sienna covers translucently. 

Some of the American siennas which are not good 
enough for staining purposes are burnt and find their 
way to the market as structural steel paints and railroad 
paints of the brownish red order; as such they are remark- 
ably good in their protective quality against corrosion. 

No standard of composition can be given, as burnt 
ochre varies very much in the percentage of iron, some 
of the burnt ochres ranging as low as 30 per cent iron 


THE BROWN PIGMENTS 79 


oxid and others as high as 7o per cent, the balance in 
both cases being clay. 


PRINCE’S METALLIC OR PRINCESS MINERAL BROWN 


This is one of the best known paints, and has had a 
successful career for more than fifty years. It is a very 
pleasing brown pigment, which has an enormous use all 
over the United States for painting wooden freight cars 
and for painting tin roofs. Where it is applied to a flat 
surface like a tin roof it has been used for many years 
in its dry state, and mixed with half raw and half boiled 
linseed oil in the field. It is at times fairly fine, and 
while it is an excellent preservative for steel it may be 
regarded as a better preservative coating for wood, two 
coats on many of the wooden barns in the country in 
the States having lasted ten years. The analysis of the 
material varies very much. 

Geologically, the ore is 
a carbonate, and lies be- 
tween the upper Silurian 
and lower Devonian. It is 
a massive material of bluish 
gray color when mined, 
and resembles limestone, 
although it contains a very 
low percentage of lime. 
The process of mining 1s 
by shaft-work. -The ore wo, 3g, 





PRINCE’S METALLIC — Photo- 
itself lies between two hard micrograph X300. 


rocks and rarely ever ex- 

ceeds three feet in width, and as a consequence the mining 
is an expensive operation. The ore is hauled to the 
kilns, where it is roasted, which drives off the carbon 
dioxid and converts it into a sesqui-oxid. The milling 


80 CHEMISTRY AND TECHNOLOGY OF PAINTS 


is the ordinary process used in grinding any of the iron 
oxids. 

The material was originally manufactured by Robert 
Prince of New York, who became interested in a slate 
quarry located in Carbon County, Pennsylvania, from 
which locality the original material came. 

A fair analysis of this material is as follows: 


Oxid’ of Iron (6:02) a eee 48.68% 
Silica xc). 6 CSc ee Pee ee avi 
Alvtiinias.25 2 ose. eee ee 12.007) 
Lime 0.5 2 ee eee 25027, 
Magnesian i: Wguccs evn os ae ere 1 e255 
Lossonelenition.- Sane ee ee 2.34% 
Undetermined = 5) 4386 ee 0.26% 

100.00% 


As the material is not alkaline, the lime and magnesia 
are undoubtedly combined with the silica, so that the 
material other than oxid of iron is silicate of alumina, 
lime, and magnesia. Sometimes, the percentage of FeO; 
will run below 40 and sometimes it will go as high as 50, 
but this really makes no difference in the paint, and in 
view of the fact that it is a natural product and may 
from time to time contain a little gang rock some leeway 
must be given as regards its composition. 


VANDYKE BROWN 


Vandyke brown is a native earth, and is identical 
with cassel brown. It is popularly supposed that 
Vandyke first used this pigment as a glazing color in 
place of bitumen, and as it is composed of clay, iron oxid, 
decomposed wood, and some bituminous products, it is 
fairly translucent and adapts itself for glazing purposes. 
Because of the bitumen which it contains, it dries very 
badly and very slowly, and has a tendency to crack or 


THE BROWN PIGMENTS 


wrinkle if the under-coat is either too hard or too soft. 
Concerning its permanence, there can be no doubt that 
it darkens considerably on exposure, like all the bitumi- 
nous compounds, and many painters use a permanent 


glaze composed of a 
mixture of ochre and 
black tinted with 
umber. Where the 
effect of age is to be 
simulated, there is 
no objection to its 
use. 

This pigment is 
used in mixed paints, 
principally on ac- 
count of its deep 
shade and. trans- 
lucent appearance. 


It contains upwards of 60 per cent of organic matter. 





No. 39. VANDYKE BROWN X38o. 


A typical analysis would be as follows: 


Organic Matter 
HEC xId oe, 
Calcium Carbonate 
Potash and Ammonia Salts 
NEOISLUECG a So ee 


1 “Materials for Permanent Painting” by Maximilian Toch. 


eae DE Pere RN AE ER esa 65%. 
fh ee Re eR aes 3% 
ee ka VE hry OT 5% 


iD Mee rapes: 2, 


Weak et ht pe cee 25% 


100% 


CHAPTER VII 
THE BLUE PIGMENTS 


THE blue pigments usually used in the paint industry 
are artificial ultramarine blue, artificial cobalt blue, and 
Prussian blue. The types of Prussian blue vary very 
greatly with their manufacture, and are known under 
the names of Milori blue, Bronze blue, Chinese blue, 
Antwerp blue, Paris blue, etc. 

Ultramarine and cobalt blues are permanent to light 
and alkali-proof. The Prussian blues are permanent to 
light, but not alkali-proof. 


ULTRAMARINE BLUE! 


Ultramarine blue, whether it is artificial or genuine, is 
chemically the same, with the one difference that the 
genuine ultramarine blue is the powdered mineral known 
as lapis lazuli, and ordinarily is the blue known under 
that name. Furthermore, the mineral itself is found at 
times in an impure state either admixed with slate or 
gang rock, or contaminated slightly with other minerals, 
and the genuine ultramarine blue may run, therefore, 
from a very deep blue to a very pale ashen blue; in fact, 
the lapis lazuli which lies adjacent to the gang rock is 
ground up and sold under the name of ultramarine 
ashes, which is nothing more nor less than a very weak 
variety of genuine ultramarine blue. 

From the standpoint of exposure to light or drying 
quality, the artificial ultramarine blue is just as good 


1 “Materials for Permanent Painting,’ by Maximilian Toch. 
82 


THE BLUE PIGMENTS 83 


as the genuine, and the only advantage that the genuine 
has over the artificial is that the genuine is not so quickly 
affected by acids as the artificial is. 

It may be of interest to know that in 1814 Tessaert 
observed the accidental 
production in a soda oven 
at St. Gobain (France) of 
a blue substance which 
Vanquelin declared to be 
identical with lapis lazuli. 
In the following year the 
same observation was 
made by Huhlmann (at 
St. Gobain in a sulphate 
oven) and by Hermann 
in the soda works at 
Schoenebeck (Prussia). PRES ae 

In 1824 La Société d’Encouragement pour Industrie 
offered a prize of 6000 francs for the production of artificial 
ultramarine blue, which, 
in 1828, was awarded to 
J. B. Guimet, a pharmacist 
of Toulouse, later of Lyons, 
who asserted that he first 
produced ultramarine in 
1826. Vanquelin was one 
of the three “trustees,” 
holding the secret contrary 
iG the ule ors thesocicre. 

In=Decembergers2a, 
Gmelin of Goettingen ex- 
No. 41. Urrramarrne Bie, ground in plained his process of mak- 

eee eectopiaph | X42: ing artificial ultramarine 
before the Académie des Sciences of Paris. He used as 








84 CHEMISTRY AND TECHNOLOGY OF PAINTS 


the basis a mixture of precipitated hydrate of alumina 
and silex, which was later on superseded by China clay 
(kaolin). 

In 1829 Koettig produced ultramarine at the Royal 
Saxon porcelain factory at Meissen. 

In 1834 Leverkus, at Wermelskirchen, and later at 
Leverkusen, on the Rhine, produced the pigment. 

In 1837 Leykauf & Zeltner, at Nueremberg, introduced 
the manufacture of ultramarine into Germany. 

Prices of ultramarine in 1830: 


Nev evita. or eee se eee $50.25 per pound 
Artiicral aces eee 4.05 per pound 


Ultramarine is composed of alumina, silica, soda, and 
sulphur, as follows: 

Ultramarine (pure blue) containing a minimum of 
silica seems to be a more or less well-defined chemical 
body, i.e., a double silicate of sodium and aluminium 
with sulphur as a poly-sulphide of sodium, or as a thio- 
sulphate. 


Ultramarines Poor Rich 
in Silica in Silica 


Alumina... (ee sor. ee ee 20/00) e227 70 
Silica Se oe bee ee 38.50 40.80 
Sodas) Rohe Mere. sevens te 22,50) (456.40 
Sulphuter eee. ae oc, se 8.201, E60 
Undecomposed iin ees 1.80%, a2ebo 





I00.00 [00.00 
R. Hoffman gives the following proportions: 


Alumina — Silica 
Pooranisilies a eee 100 128 
Rich in.silica 2 eee eee 100 170 


THE BLUE PIGMENTS 85 


In resistance to alum the different products rank as 
follows: 


ANUS) 1 and TE Sai apace aa any Sere First 
Artif. Ultramarine (rich in silica). ... Second 
Artif. Ultramarine (poor in silica) ... | Third 


In 1859 Leykauf discovered the purple and red varie- 
ties of ultramarine, which were produced by the action 
of hydrochloric and nitric acids, and by heating ultra- 
marine with calcium chloride, magnesium chloride, and 
various other chemicals. In this way there were pro- 
duced a variety of shades, and by the addition of such 
substances as silver, selenium, and tellurium, even yellow, 
brown, purple, and green shades were produced. 

All of these colored ultramarines are exceedingly 
permanent to light, but have little or no hiding power, 
and when used alone are perfectly permanent. 

The ultramarine blue which is made by means of a 
potash salt instead of a soda salt has every analogy of 
color and shade to genuine cobalt blue, excepting that 
the genuine cobalt blue is not affected by acids as 
rapidly as the artificial. 


ARTIFICIAL COBALT BLUE 


The cobalt blue of commerce is the same as _ ultra- 
marine blue, the difference being in the shade. Ultra- 
marine, when mixed with thirty parts of a white pigment, 
such as zinc oxid, produces a violet shade, whereas the 
cobalt blues when mixed in the same proportion produce 
a turquoise or sky-blue shade. Chemically, the com- 
position of these ultramarines and cobalts will average 
about 50 per cent silica, 22 per cent alumina, 15 per cent 
sodium sulphide, in combination with 3 per cent water 
and ro per cent sulphur. The addition of the slightest 


86 CHEMISTRY AND TECHNOLOGY OF PAINTS 


trace of acid to a paint containing ultramarine blue 
liberates H.S, which always indicates the presence of 
ultramarine in a blue or bluish pigment. Under the 
microscope ultramarine blue has a distinct crystal- 
line appearance. When these crystals are badly de- 
stroyed by fine grinding the color suffers very much, the 
characteristic brilliant blue of ultramarine becoming an 
exceedingly muddy shade. Its tinctorial power is very 
weak, but it is exceptionally permanent to light. In 
blue shades of mixed paints 
the percentage of ultra- 
marine blue can be deter- 
mined either by difference 
or by the percentage of 
sulphur “present. aie 
per cent is accepted as 
the amount of sulphur in 
ultramarine blue, a fairly 
accurate quantitative de- 
termination can be arrived 
at. Where ultramarine blue 
No. 42. Dry ULTramarine BLUE— is mixed with lithopone the 

Photomicrograph X320. zinc sulphide of the litho- 
pone as well as the ultramarine evolve H.S. When deter- 
mining the ultramarine, the total H.S evolved must be 
calculated as sulphur. The zinc must be precipitated as 
carbonate and weighed as oxid and calculated to sulphide. 
The sulphur in the ZnS must then be deducted from 
the total sulphur. From the difference the percentage 
of ultramarine blue in the original pigment may be cal- 
culated. . As ‘acetic acid <liberates the Tipo eiirommeann. 
ultramarine but does not attack the S in lithopone, this 
acid may be used and the percentage of sulphur in the 
ultramarine determined directly. 





THE BLUE PIGMENTS 87 


Ultramarine blue reacts with corroded white lead 
but not with zinc oxid. It does not react very quickly 
with sublimed lead or zinc lead, but for the making of 
pale blue shades, which should remain permanent in the 
package, zinc oxid is to be recommended in preference 
to any other white pigment. Ultramarine blue should 
not be mixed with any of the chrome yellows or chrome 
greens, because a darkening effect is sure to take place. 
Ultramarine blue behaves very badly with linseed oil 
containing an excessive amount of lead drier. For mixed 
paints of pale tints a resinate of manganese or oleate of 
manganese drier is to be recommended. Most of the 
Japan driers contain large quantities of lead, and a white 
Japan composed of rosin, manganese and linseed oil will 
make the most permanent mixture. 


PRUSSIAN BLUE 


Synonym: Milori Blue, Bronze Blue, Antwerp Blue, Chinese Blue, 
Paris Blue, etc. 

Almost every text-book on elementary chemistry 
gives a description of Prussian blue, which is a ferri-ferro- 
cyanide of iron, and in a general way it can be produced 
for laboratory purposes by the simple mixture of ferro- 
cyanide of potassium and a ferric salt of iron. Com- 
mercially, the well-known ferric iron reaction of analytical 
chemistry is reproduced on a large scale. Prussian blue, 
however, is made from a ferrous salt and is obtained by 
the mixture of ferrous sulphate (copperas) and ferro- 
cyanide of soda or potash (yellow prussiate). This mixture 
produces a pale bluish white flocculent precipitate, and the 
chemist will easily understand how, with the addition of 
any oxidizing agent, such as bleaching powder, potassium 
chlorate, etc., the precipitate is converted from a bluish 
white into a dark-blue pigment. 


88 CHEMISTRY AND TECHNOLOGY OF PAINTS 


There are a number of varieties of Prussian blue, all 
approximating this composition but made differently, 
being sold under the names of Steel blue, Milori blue, 
Bronze blue, Antwerp blue, Chinese blue, and Paris blue. 
Although each of these blues is chemically the same as 
Prussian blue, they have different physical character- 
istics. Prussian blue, for instance, is like a mixture of 
indigo and black in its dry state, and when tinted with 
one hundred times its own weight of zinc oxid the shade 
produced is a muddy violet. Chinese blue, when treated 
in the same manner, gives a purer blue which has no 
trace of violet in the shade. The Steel blue, when diluted 
one hundred times, gives a turquoise shade. And so for 
the manufacturer of pale blue shades the tones of these 
blues must be taken into consideration. 

There is much discussion among paint manufacturers 
as to whether Prussian blue is a permanent pigment or 
not, and the author is frank to say that this matter can 
be decided as follows: Prussian blue, or any of its varieties 
may be considered permanent or fugitive, according to the 
manner in which it is made and according to the base 
with which it is mixed. If Prussian blue contains more 
than a trace of soluble salt (sodium sulphate), it has a 
decidedly yellowing action on the oil, and a light blue 
or light green made of such Prussian blue is supposed to 
be fugitive. On the other hand, a number of experi- 
ments made with thoroughly washed Prussian blue have 
demonstrated that it is a perfectly stable color and does 
not change its shade. As a tinting color for making pale 
blues in mixed paints Prussian blue has caused an enor- 
mous amount of trouble. A pale blue mixed paint that 
contains white lead in any proportion changes color in 
the package, a reduction process taking place which 
converts it from a ferric into a ferrous state, so that 


THE BLUE PIGMENTS 89 


when a can of light blue mixed paint made with Prussian 
blue and white lead is opened it is a sickly green instead 
of a blue. If such a paint be applied to an exterior 
surface it is completely converted into its original blue 
shade as soon as it is dry. ‘The zinc oxid paints have the 
same action, but to a very small degree, and a paint 
manufacturer who desires to make a pale blue by the use 
of Prussian or Chinese blue must avoid the use of white 
lead in his paint. The artificial cobalt blue mixed with 
zinc oxid is, however, more desirable. 

Prussian blue is also used in small quantities for mix- 
ing with bone black to produce intensely black shades. 

It is a simple matter to determine the presence of 
Prussian blue in any pigment by the addition of caustic 
soda to the dry extracted pigment, warming, filtering, 
and testing the filtrate with a drop of ferric chloride after 
acidifying. The Prussian blue made in _ laboratories 
will contain approximately 30 per cent of iron, so that if 
an analysis is made of a mixed paint tinted with Prussian 
blue and the percentage of iron is multiplied by three, a 
fairly correct estimate of the percentage of Prussian blue 
is obtained; and while the factor given cannot be abso- 
lutely correct, owing to the difference in the various 
blues made, it is so nearly correct that a synthesis made 
from such an analysis has invariably given the same 


shade. 


CHAPTER VIII 
THE GREEN PIGMENTS 


THE greens used in the manufacture of paints are 
the so-called chrome greens, which are mixtures of chrome 
yellow and Prussian blue, the genuine chrome greens or 
chromium oxid, the aniline lakes and verte antique or 
copper green. 


CHROME GREEN 


Chrome green is sold under various proprietary names, 
and must not be confounded with the oxid of chromium. 
Chrome green is essentially a mixture of Prussian blue 
with chrome yellow, but the chrome greens, unless chemi- 
cally pure, are always mixtures of blue and yellow on a 
barytes or mixed base. 7 

A green paint made entirely of Prussian blue, chrome 
yellow, and an inert base, such as silica or barytes, is 
very easily analyzed by ignoring the pigment and weigh- 
ing the base, calculating the pigment by difference. This 
is, however, not a desirable method to recommend except 
in the hands of an expert who knows that the pigment or 
paint is made on an inert base. Inasmuch as there is a 
great variety of shades of chrome green, ranging from a 
yellowish green to a very dark olive, and as the dark 
shades may be composed of either a mixture of orange, 
chrome yellow, and Prussian blue, or a light chrome 
yellow and Prussian blue and black, it is not safe to 
multiply the percentage of iron by a factor to obtain the 
percentage of Prussian blue, because many shades of 

go 


THE GREEN PIGMENTS QI 


green are produced with the use of ochre. The iron 
factor would therefore be misleading. The lead chro- 
mate can be washed out with hot hydrochloric acid and 
will precipitate on cooling. The Prussian blue may be 
washed out with a caustic alkali solution, the iron being 
left behind, but it can be reprecipitated as Prussian blue 
with a ferric salt, the necessary amount of chrome yellow 
and Prussian blue originally used being thus recovered. 
This method is uncertain only when an olive-yellow is 
being analyzed. 

Chrome green should never be mixed with white lead 
for the pale shades, as it changes color in the can in 
proportion to its content of Prussian blue. Zinc lead, 
zinc oxid, sublimed lead, or lithopone should therefore 
be used. If chrome green is not well washed the soluble 
salts are likely to affect the linseed oil. At the seashore 
the salt atmosphere invariably attacks chrome green and 
bleaches it, and where an absolutely permanent green is 
required chromium oxid should be used. 


CHROMIUM OxID 
Chemical Formula : Cr.O3 


This green is one of the oldest greens in existence, 
having been used for very many years, but never having 
been used for mixed paints or by the paint manufacturer, 
excepting for artists’ use, until within the past six years. 
While it is expensive compared to the chrome green as 
previously described, and while it is weaker in tinting 
power and lacks in brilliancy, it nevertheless is the only 
perfectly permanent green made. It mixes with every 
other pigment without decomposition and stands the 
light without fading or darkening. No alkali discolors 
it, and therefore in the modern flat wall paints where 
delicate greens are desired chromium oxid has come to 


Q2 CHEMISTRY AND TECHNOLOGY OF PAINTS 


play a very significant réle. Many manufacturers get 
more for their fancy colors, such as greens, blues, and ver- 
milions, and any man who makes a perfectly alkali-proof 
wall paint is entitled to a higher price if the goods are 
better than those of his competitor. 

Chromium oxid frequently possesses coarse qualities. 

It is made by fusing a chromate or dichromate with 
sulphur, the reaction being: 


K.Cr,O, ae S ea Cr.O3 =i K.SOu; 


or it can be made by calcining the hydroxid Cr.(OH), 
which is easily made by precipitating a chromic salt with 
an alkali. 

After it comes out of the dry room it has to be ground 
in a burrstone mill with water exactly like an oil color. 
This develops whatever brilliancy there is in the color 
and increases its hiding power, but unfortunately it also 
develops a “float” of a very much more brilliant green 
than the natural chromium oxid. This float is similar 
in color to the well-known Veronese green or hydrated 
oxid of chromium, but is not apparent in the quicker 
drying types of paints. 

Chromium oxid is now largely used as a basic color 
in automobile painting, particularly in the painting of 
the hoods, and also for the manufacture of the best 
type of dark green engine enamels, because excessive 
heating, or alternate heating and cooling, does not affect 
it in shade as it does the chrome green made from yellow 
- and blue. 

There is every reason to believe that this pigment 
will be used in greater quantities than it has been, because 
of its sterling qualities. 


THE GREEN PIGMENTS 93 


GUIGNET’S GREEN OR HYDRATED CHROME OXID 
Syn.: (Viridian, Emerald Oxid of Chromium, Veronese Green) 


This color has practically the same properties as Cr.Os. 
It has a brighter, deeper shade, however, and is more 
transparent than the oxid, having a brilliant emerald 
undertone. 

It is made by fusing at a dull red heat about 32 parts 
of potassium dichromate with 8 parts of boric acid, and 
plunging the hot mass into water. The color is then washed, 
jn boiling water, and ground. ‘The reactions have been 
explained by Zerr & Rubencamp as being: 

1% ges + 16B(OH)3 = Cre(BsO7)3 + K2Bs0O7 + 25H2O 

+ 30. 

2. Cri(B,0)s + 2H.,O = CreO(OH)s + 12B(OH)s. 

Being extremely inert and permanent to light, heat 
and acids it finds the same uses as chrome oxid, but more 
limited on account of its higher cost. 


VERTE ANTIQUE (COPPER GREEN) 


The pigment for making verte antique or antique 
green for copper imitation is generally the bicarbonate of 
copper. It has little or no hiding power, but the corroded 
copper effect cannot be very well imitated with any other 
pigment. It is manufactured as follows: 

A solution of blue vitriol is precipitated with sodium 
carbonate, yielding a basic copper carbonate, carbon 
dioxid being evolved in the course of the reaction. 


2CuSO, + 2NaesCO; + H,O = CuCO;-Cu(OH)s + 2NaeSOu4 + COan. 


There are a number of other methods in use for 
making copper green which are more lengthy and trouble- 
some to carry out. 

The lack of hiding power of this color is one of its 


04 CHEMISTRY AND TECHNOLOGY OF PAINTS 


good qualities, because the under coat usually is a copper 
color, made by so mixing a para toner and Princess Metal- 
lic brown that the translucency of the bicarbonate of 
copper gives the effect of actually corroded copper. 
Frequently this color is stippled on, and sometimes it is 
flowed on. Where opacity or hiding power is wanted 
chromium oxid and bicarbonate of copper are mixed. 
This pigment is permanent to light, and is at present 
practically the only pigment made or used which con- 
tains copper. 


GHAPTER EX 
THE BLACK PIGMENTS 


THE principal dry pigments used in making black 
paint are as follows: 


Lampblack Vine Black Black Toner 
Carbon Black Coal Benzol Black 
Graphite Ivory Black Acetylene Black 
Charcoal Drop Black Mineral Black 


There are quite a large variety of bone blacks, begin- 
ning with ivory black and going down to the by-product 
of the sugar mills known as ‘Sugar House black.’ In 
composition all of the animal blacks are alike, in so far 
as they always contain carbon and calcium phosphate. 
The carbon varies between 15 and 23 per cent, the 
rest being phosphate of lime and moisture. Some of 
the best blacks used for mixed paints are made from 
the shin-bone and skull of the sheep, it having been 
found that these blacks are of the most intense color. 
Occasionally variable amounts of calcium carbonate are 
found in these blacks, depending largely upon the length 
of time the bone was burned. For making a very intense 
and good quality black which will not settle when mixed 
with varnish, carefully selected bones or burnt ivory 
chips are taken, and digested in hydrochloric acid, which 
removes all the lime salts and leaves the carbon as a. 
flocculent residue. This carbon is probably the highest 
priced and most intense black used by paint makers, 

95 


96 CHEMISTRY AND TECHNOLOGY OF PAINTS 


and is frequently sold under the name of black toner, 
because it sometimes is used for giving an intense tone 
to an otherwise pure black. In the material known as 
Black Color in Varnish, it is found that black toner 
serves its purpose best, and a black paint which is com- 
posed of black toner ground in linseed oil and reduced 
with a very high grade of coach varnish is worth from 
$4 to $6 per gallon. 


LAMPBLACK 


Lampblack is the condensed smoke of a carbonaceous 
flame, and at present is made from a hydrocarbon oil 
of the type of dead oil, or it may be made from a number 
of distillates which on burning give a condensed black 
soot. Lampblack is still made from resinous woods, 
tar and pitch where the dead oil is not obtainable, and 
while many people are inclined to regard lampblack and 
carbon black as the same, they are not by any means the 
same from the paint manufacturer’s standpoint, for lamp- 
black is distinctly gray when compared with ivory black, 
bone black, or carbon black, and as a general rule lamp- 
black makes a bluish gray when tinted out with white, 
one hundred parts to one, whereas bone black and ivory 
black as a rule make a brownish tint. This is an empiri- 
cal method for differentiating them. 

The specific gravity of lampblack is generally less than 
two, and one pound of a very pure lampblack without 
undue pressure will fill a package which is over 200 
cubic: inches in size, and very often Over=230" cubic 
inches or one American gallon. 

Lampblack is distinctly an American product, as is 
evidenced by the enormous amount of blacks of this type 
which are exported; a careful search of the imports fails 


THE BLACK PIGMENTS 97 


to show any appreciable amount which comes into this 
country.! 

Lampblack as it is made now is exceptionally pure, 
and contains more than 99 per cent of carbon. Occasion- 
ally, however, samples are found which contain a small 
percentage of unburned or condensed oil, which will 
retard the drying of lampblack to such an extent as to 
make it at times unfit for use. Prior to 1906 there were 
many cases where lampblack contained unsaponifiable 
- grease, and the author de- 
vised a method for remov- 
ing this with 62° naphtha, 
changing the slow drying 
lampblack into one which ~ 
dried definitely; but smce § 
that time, due to improve. 
ments in the selection of — 
lampblack and the greater 
care taken in its manu- 
facture, it is very difficult 
to find a lampblack which 
contains less than 99.5 per 
cent carbon and which 
does not dry within a reasonable time. It must be taken 
into account that lampblack is always a slow drier. 
Whether this is due to the fact that it prevents the blue 
rays of light from entering the oil, or whether it is an 
inherent paralysis, has not been definitely decided, but one 
thing is positive, that where lampblack contains unburned 
or condensed oil the drying is in a large measure paralyzed. 





No. 43. LAMPBLACK — Photomicrograph 
X300, very uniform. 


1 A most excellent historical treatise on lamp and carbon blacks ~ 
will be found in the original communications of the Eighth Inter- 
national Congress of Applied Chemistry, Volume 12, page 13, by 
Godfrey L. Cabot. 


98 CHEMISTRY AND TECHNOLOGY OF PAINTS 


CARBON BLACK 


Carbon black is in all respects similar to lampblack, 
except that it is intensely black in color, and while it 
shows no crystalline structure under the microscope it 
condenses itself so hard on the places from which it is 
scraped that it is largely interspersed with flakes of black 
which to all appearance are crystalline and are very 
refractory in the mill. Its tinctorial power is very great, 
one pound being sufficient 
to tint one hundred pounds 
of white lead to a dark 
gray. Paint manufacturers 
have, however, abandoned 
its use as a tinctorial ma- 
terial for several reasons, 
the principal ones_ being 
that it is likely to produce 
a streaky color when used 
as a tint, owing to the pres- 
ence of very small nodules 
that do not show up until 
it is applied as a paint 
(and these streaks cannot be brushed out). In the 
second place it shows a peculiar tendency to attach 
itself to minute air bubbles, so that when made into a 
mixed paint of a lighter tint and allowed to stand in the 
package for a considerable time, fairly large amounts of 
black rise to the top of the liquid. Only with the great- 
est difficulty can these be remixed with the rest of the 
pigment to produce a uniform tint. 





No. 44. CARBON BLAck — Photomicro- 
graph x300, very uniform. 


THE BLACK PIGMENTS 99 


GRAPHITE 


Synonym : Black Lead, Stove Polish. Specific Gravity: 1.19 to 2.5, 
depending upon the impurities contained in it 


Graphite is found as a mineral almost all over the 
world. It is very largely used as a paint pigment, and 
it is remarkable that in its natural state it has all the 
defects of bulkiness which red lead has for weight. The 
purer a paint pigment is as to its content of carbon the 
poorer is the paint pro- 
duced. If graphite be taken 
with a content of 80 or go 
per cent carbon and mixed 
with linseed oil, it forms a 
porous, fluffy film, and the 
particles of graphite coagu- 
late in the linseed oil and 
produce a very unsatisfac- 
tory covering. If graphite 
be diluted with a heavier 
base its weakness then be- 





a No. 45. NaturaL GRAPHITE — Photo- 
comes Its strength and a micrograph X250, containing about 


very good paint is formed. 40 per cent of silica, showing crystals 


Ses of silica and graphite. 
Many of the characteristic hs 


chemical and physical defects of red lead are largely 
reduced and frequently eliminated when it is mixed in 
proper proportion with graphite, a high grade of graphite 
when finely ground with linseed oil acting as a lubricant 
and sliding under the brush. 

Pure graphite, as is well known, will cover from 1000 
to 1600 square feet to the gallon. Such a paint film is 
so exceedingly thin that, while it looks good to the eye, 
in a short period decomposition more easily takes place 
beneath it than beneath many poorer paints. It is there- 


100 CHEMISTRY .AND TECHNOLOGY OF PAINTS 


fore essential to reduce graphite with a heavier base, and 
to this end it has been found that a mixture of silica 
and graphite produces very good results; but even this 
paint has the objection of having too much spreading 
power. 

Misnomers have crept into the paint trade in regard 
to graphite paints, such names as green graphite, red 
graphite, brown graphite, etc., being in use, when in 
reality such graphites do not exist, excepting as far as 
graphite has been mixed with pigments of these colors. 

eee EES A six-year test of a 
Tt, linseed oil paint made with 


4 ~ 7 te > a neutral ferric oxid, con- 
A ee i . taining in its composition 


75 per cent ferric oxid and 
ee ‘s tn. * 20 per cent silica “mixed 
2 : : & - with graphite containing 85 

%, ie ® per cent graphitic carbon, 


» ai as as has proved itself to be as 


, : : good a paint as can be 

be, ey TS desired for ordinary pur- 

eesce ot poses. The pigment in a 

No. 46. NATURAL GRAPHITE — 90 per : : : ; 

cent carbon, very finely powdered. paint of this kind will 

withstand the chemical ac- 

tion of gases and fumes, but the oil vehicle is its weakest 
part. 

Since the electro-chemical industry has been developed 
at Niagara Falls graphite has been made artificially and 
is sold under the name of “Acheson Graphite.” This 
graphite is to be commended as a paint material on 
account of its uniformity and fineness of grain, but it 
should not be used alone as a pigment, for as such it 
possesses the physical defect of lightness just described. 
A graphite paint containing more than 60 per cent graph- 


THE BLACK PIGMENTS IOI 


ite does not serve its purpose very well unless 4o per 
cent of heavy pigment is added, such as a lead or a zinc 
compound. A rather unfortunate defect in the graphite 
paints containing a large amount of graphite is the 
smooth and satin-like condition of the paint film, which 
is poorly adapted for repainting. It has often been 
noted that a good slow-drying linseed oil paint will curl 
up when applied over certain graphite paints, because 
it does not adhere to the graphite film. On the other 
hand, if particular forms of 
calcium carbonate, silica, 
or ferric oxid are added 
to graphite a surface is 
presented which has a | 
“tooth,” to which succeed- 4 
ing films adhere very well. 

The question of the co- 
efficient of expansion in 
paints has not been thor- 
oughly considered, and firs 
many a good paint will No. 47. ARTIFICIAL GRAPHITE (Acheson) 
fail because it is too elastic. | ——Photomicrograph 250, contain- 

‘ ; ing go per cent of carbon. 

Engineers sometimes pre- | 

fer a paint which when scraped with a knife blade 
will curl up like ribbon. Priming coats suffer very 
much when they are as elastic as this, but the paint 
chemist can overcome these defects by the proper ad- 
mixture of inert fillers and hard drying oils. 

Graphite is known as a very slow drier, but this is 
true only when too much graphite is used in the paint. 
There is no reason why a graphite paint should not be 
made to dry sufficiently hard for repainting within 
twenty-four hours. | 






102 CHEMISTRY AND TECHNOLOGY OF PAINTS 


CHARCOAL 


It is not generally known that charcoal from the 
willow, maple, and bass trees is largely used as a pigment 
for black paints. ‘There are a number of black paints 
on the market which are composed of charcoal, lampblack, 
litharge, and linseed oil in varying proportions, and in 
the early history of these paints it was difficult to make 
them so thin that they would not turn semi-solid in the 
package. It was found that 
aS a preservative coating 
on steel they did remark- 
ably well. Investigations 
_ by the author have shown 
© that this preservative ac- 
tion is incidental and is 
due entirely to the alkali 
contained in the charcoal. 

_ / Some of the charcoal used 
aS et” is a by-product from paper 
No. 48. ARTIFICIAL GRAPHITE (Ache- mills and contains as high 

son) — Photomicrograph X250, umi- as g per cent of potassium 

eee carbonate? im? tact een. 
carbonate is produced by the burning or calcining of wood, 
most charcoal being more or less alkaline. In the exami- 
nation of paints of this character it was noticed that the 
spectroscope showed the potash lines, and thus it became a 
very simple matter to determine by means of the spectro- 
scope whether a paint was a charcoal paint or not. The 
author has demonstrated on previous occasions that the 
oxidation of metal cannot take place in the presence of 
certain alkalies, and therefore these charcoal paints when 
freshly made are excellent preservatives for the metal. But, 
inasmuch as moisture is always present in these paints, 





THE BLACK PIGMENTS 103 


having been added in the form of water or contained in 
the raw materials, saponification takes place more or less 
rapidly, so that the paints 
are sometimes unfit for 
use two months after they 
are made. 

The charcoal above re- 
ferred to, which is the 
by-product from the paper 
mills, while not so suitable 
for the manufacture of 
mixed paints, has, however, 
been very largely used in 
the manufacture of oilcloth No. 49. Five CHARCOAL — Photomicro- 
and coated leather. graph x600. 





VINE BLACK 


In all essentials this pigment is the same as the pow- 
' dered charcoals for paint 
purposes, excepting that 
the grain is smaller and the 
black denser. It is made 
in Germany by charring 
the grapevine. If over- 
charredi ites ismdikely: 3to 
become too alkaline. The 
same tests may be applied 
to this black which were 
used for all the charcoal 
and wood pulp blacks, the 





No. so. CHarcoaL BLack — Photomi- 
crograph  x600, showing hexagonal simplest and most effec- 


structure of the wood. 


tive test being to boil the 
black in water, filter, and add a few drops of phenol- 
phthalein. 


104 CHEMISTRY AND TECHNOLOGY OF PAINTS 


GOAT 


Powdered anthracite and bituminous coal are likewise 
used in black paints, but the origin of their use is due to 
some extent to poorly written paint specifications. An 
engineer will at times prescribe a paint containing a cer- 
tain percentage of ash, and in order to meet this require- 
ment a paint manufacturer will have to add coal in order 
to conform with the requirements, but as sulphur com- 
pounds such as SO, and SO; 
always exist in coal a paint 
is produced which is ex- 
ceedingly harmful to metal. 


Ivory BLACK 


Ivory black is still used 
to some extent for very 
intense coach colors, and 
there is alsoSas every enme 
AE species of carbon black on 
No. 51. VINE Biack (German make) — the market known as the 

fee ee X250, two sizes of “Extract of Ivory Black,” 

: which is made by digesting 
charred ivory chips in hydrochloric acid until nearly all 
of the calcium phosphate is dissolved. Such a black has 
intense staining power, and is by far the blackest material 
made. It is very expensive, colloidal in its nature, and 
used therefore for ready prepared color-in-varnish or high 
grade black enamels. 





DROP BEAGK 


Drop black is generally made by calcining sheep bones, 
which are then impalpably ground in water, and when in 


THE BLACK PIGMENTS 105 


paste form cast into small drops; hence its name, ‘‘ Drop 
Black.” These cone-shaped drops were largely used 
twenty-five years ago, and then were an indication of a 
good black, but at present the name “Drop Black” 
still clings to finely powdered bone black. So-called 
drop black is generally composed of from to to 20 per 
cent of carbon and from 80 to go per cent of cal- 
cium phosphate, and is sold entirely for its intensity of 
blackness. 


BLACK TONER 


Black toners may be either the extract of ivory 
black, the extract of bone black, or certain forms of 
carbon black, or carbon 
black upon which nigro- 
sine has been precipitated. 
Another method for mak- 
ing black toner is_ to 
precipitate red, yellow, and 
blue aniline upon the ex- 
tract of ivory black, which 
produces an_ intensely 
black pigment that is 
flocculent and remains 
in suspension a long time. No. 52. Woop Purtp Brack — Photo- 

The principal difficulties micrograph 500, very fine uniform 
with these coal tar blacks, 
however, are: first, they are not really black in the 
sunlight; and second, they paralyze the drying quality 
of any varnish with which they may be mixed. There 
are a number of specially fine blacks that can be used for 
black toners, such as condensed carbon from benzol or 
acetylene. Benzol black is remarkably fine and intensely 





106 CHEMISTRY AND’ TECHNOLOGY OF PAINTS 


black, and inasmuch as there may be an overproduction 
of benzol in the United States within. the next few 
years it is very likely that benzol black will become a 
reasonable article of commerce. 


BENZOL BLACK 


Benzol black is a carbon 
black which, however, ‘is 
much better than the car- 
bon black produced from 
natural gas. It is soft, 
contains no granular par- 
ticles, and remains in sus- 
pension for many weeks 
in both oil and varnish. 
It is, however, a very poor 
drier, like most of these 
blacks, and therefore a 
mixture of litharge and red lead oil is recommended 
when they are to be used. 





No. 53. Drop Brack — Photomicro- 
graph x<300, not very uniform. 


ACETYLENE BLACK 


This black is not quite 
as common as it was some 
years <avO. “Ll. Masuuverm 
desirable properties and 
‘can be used for tinting 
purposes without showing 
granules or streaks, as is “oh, 
often the case with car- No. 54. Drop Brack — Photomicro- 
bon black made from graph x300, very finely powdered. 


gas. It is flocculent and somewhat colloidal in nature. 





THE BLACK PIGMENTS 107 


MINERAL BLACK 


Mineral black is usually composed of heavy black 
slate, more or less finely ground, and as a paint pigment is 
inert. It is often toned with lighter (in specific gravity) 
carbons and lampblacks, but is not largely used on 
account of its destructive action on paint mills. Where 
iron paint mills are used these mineral blacks are found 
to be very expensive, because they will dull the sharpest 
mill in a few hours’ run. As they possess very little 
tinctorial power it is more advantageous to use a 200- 
mesh silica, tinted with lampblack. 


ANALYSIS OF MINERAL BLACK 


Silicate of Alumina (clay)........... 65 to 70% 
MeEPOUSsRCTLICcOXI0 <5 stein he. 10 to 12% 
Carbonaceous matter, balance up to 100%. 


CHAP LH Rae 
THE INERT FILLERS AND EXTENDERS 


THESE materials, which at times have been called the 
“reénforcing pigments,” have their value when used in 
moderate proportions, and yet it is not within the 
province of any paint chemist to say to what extent 
these materials can be classed as adulterants and to 
what extent they can be classed as inert fillers or reén- 
forcing pigments. In every case where this question 
comes up common sense, judgment, and best practice 
provide the answer. 

In the manufacture of mixed paints, with one excep- 
tion which will be described later, every mixed paint 
must contain an inert filler or extender, or else the paint 
will not remain in a ready-to-use form, but will set hard 
and lose much of its value. In white paints 45 per cent 
of zinc, 45 per cent of lead, and ro per cent of asbestine 
is regarded as a standard formula, and 60 per cent of 
these pigments are usually mixed with 4o per cent of oil 
to produce the proper kind of paint. There are many 
instances where the inert fillers may reach as high as 20 
per cent, that 1s, to 4o per cent of zinc and 4o per cent 
of lead or other white pigments, 1o per cent of gypsum 
and ro per cent of white mineral primer are added in 
order to give certain physical results; and yet there are 
any number of instances where more than half of the 
paint in question is composed of an inert filler, and the 
inert fillers under those circumstances cannot be regarded 


108 


THE INERT FILLERS AND EXTENDERS 10g 


as adulterants. If we make a ready mixed paint of 
ochre we are taking a natural pigment which contains 
80 per cent of clay, and no man can say that the clay 
naturally contained in ochre is an adulterant. In the 
manufacture of a flat wall paint in which lithopone is 
the principal pigment we have a pigment which contains 
70 per cent of artificial barium sulphate, and yet no man 
can say that this artificial barium sulphate is an adul- 
terant. In the Battleship Gray paint which the author 
devised for the United States Navy, it was found that 
the 45 per cent of zinc and 45 per cent of lead, with the 
addition of to per cent of black coloring matter, which 
was formerly used, gave very poor results, for such a 
paint was not salt-water-proof nor resistant to abrasion; 
but since the United States Navy has adopted the for- 
mula made by the author of 45 per cent of zinc oxid, 45 
per cent of blanc fixe, and to per cent of graphite and 
lampblack, a far better paint is produced which costs 
the Navy very much less money than the old type of 
paint. It is therefore not within the province of any man 
to say that the addition of this 45 per cent of blanc fixe 
constitutes an adulterant. Judgment, common sense, and 
the particular case involved must therefore decide the 
difference between pigment and adulterant. A large 
number of other cases can be cited, but these are suf- 
ficient to illustrate the point. 

The principal paint made which aang no extender 
and which remains in suspension is the well-known white 
enamel paint composed entirely of zinc, in which the 
medium is either a heavy bodied oil or a damar varnish. 
This paint needs no extender to keep it in suspension, 
on account of the very slight chemical action that takes 
place between the acids in the oil or varnish and the zinc 
itself. 


IIO CHEMISTRY AND TECHNOLOGY OF PAINTS 


In spite of all the good qualities of white lead it has 
been impossible up to now to manufacture a ready mixed 
paint composed entirely of white lead without the help 
of an extender like asbestine or a slight saponification 
or emulsification by the addition of about 1 per cent of 
water. 

It is not so difficult to decide what constitutes an 
adulteration if we take the simple case of ready mixed 
white paint intended as a priming coat, which should 
have the maximum hiding power and physical qualities. 
If a paint like that were composed of 50 per cent white 
pigment and 50 per cent of barytes or whiting, it would 
not possess the physical qualities necessary for a good 
priming paint, and therefore the addition of this quantity 
of barytes would be strictly regarded as an adulterant. 

The principal fillers used in the manufacture of paints 
are as follows: 


Barytes Calcium Sulphate 
Barium Sulphate, (Artificial) Clay 

Barium Carbonate Kaolin 
Silica Asbestine 
Infusorial Earth White Mineral Primer 
Calcium Carbonate Whiting 
Gypsum 


BARYTES (BARIUM SULPHATE, NATURAL) 
Formula, BaSO,; Specific Gravity, 4.5 


Barytes is a white mineral having the same chemical 
composition as precipitated barium sulphate. In the 
United States Geological Survey Reports for 1904, the 
following statement occurs: ‘‘The value of barytes as a 
white pigment is being recognized more and more each 
year, and although very little, if any, is used alone for 
this purpose, it is used in large quantities in. combination 


THE INERT FILLERS AND EXTENDERS III 


with white lead, zinc white, or a combination of both of 
these white pigments. This addition is not considered 
an adulteration, as was the case a few years ago, for it 
is now appreciated that the addition of barytes makes a 
white pigment more permanent, less likely to be attacked 
by acids, and freer from discoloration than when white 
lead is used alone. It is also believed that barytes 
gives greater body to the paint and makes it more 
resistant to the influences of the weather. As is well 
known, pure white lead 
when remaining in the 
shade or in a dark place 
becomes discolored, turn- 
ing yellowish, while mix- 
tures of white lead and 
zinc white, or white lead 
and barytes, or white lead, 
zinc white, and barytes 
retain their color perma- 
nently even in dark places.” 

The amount of barytes 
that can be mixed with 
colored pigments without | 
injuring them is remarkably large. There are hundreds 
of brands of para-red paints made and consumed every 
year by the agricultural implement trade which contain 
as high as go per cent of natural barytes. When it is 
taken into consideration that these extremely diluted 
para-reds cover well and serve their purpose most admir- 
ably, the expert should be very careful not to condemn 
barytes when used in large quantities, for this remarkable 
behavior is repeated with a large number of other pigments. 

No paint chemist will dispute the fact that barytes 
adds wearing quality to paint, but inasmuch as white 





No. 55. BARYTES, irregular, broken crys- 
tals— Photomicrograph x300. 


Lig CHEMISTRY AND TECHNOLOGY OF PAINTS 


lead has set the standard for ease of working it is ad- 
mitted that all the other pigments and fillers are not as 
unctuous as white lead. Therefore the house painter 
will notice that the so-called lead combination, which 
contains large quantities of barytes, does not work as 
freely under the brush as white lead; nevertheless, this 
objection does not hold good when the barytes is used 
in moderate quantities, that is, not in excess of one third 
of the total pigment of a paint. An experiment was 
made with a mixture of one third carbonate of lead, one 
third zinc oxid, and one third barytes on an exposed wall 
of a high building in New York City, in 1885.! Up to 
190s this surface was still in a moderately good state of 
preservation, and as a comparison a wall painted in 1900 
with a pure Dutch process white lead showed that the 
Dutch process white lead had not stood as well in five 
years as the combination mixture had stood for twenty 
years. It is conceded that no paint is supposed to last 
twenty years, but as a matter of record it is interesting 
to note that the inert filler added so much to the life of 
the paint which contained it. In view of this fact, the 
paint manufacturer is justified in recommending to his 
customers the use of inert fillers in his paint on the 
ground of increased longevity. 

One hundred pounds of barytes will yield two and 
three-quarters gallons of paint. Owing to its crystalline 
structure and specific gravity it is a more expensive pig- 
ment to use than many others when sold by volume, and 
a paint manufacturer who uses barytes in a mixed paint 
and thinks he is the financial gainer thereby is very much 
mistaken, owing to the small volume which barytes occu- 
pies in a mixed paint. It is also interesting to note from 
an experimental standpoint that if barytes be mixed with 


' This building was demolished in 1908. 


THE INERT FILLERS AND EXTENDERS 112 


linseed oil and turpentine in the proportion of two pounds 
to a gallon it will be found that, on allowing these two 
pounds to settle in a glass jar where it can be observed, 
it occupies only 4 per cent of the bulk. In spite of 
much that may be said in favor of barytes, it is not 
better than some of the forms of calcium carbonate and 
some of the forms of silica. As an inert extender silica 
has advantages over barytes; namely, that while it 
produces the same physical effects with equal wearing 
quality, its cost is lower 
and it produces a surface 
for repainting, having what 
is technically known as 
“tooth.” 

Barytes is made from 
the mineral barite, and 
the principal deposits in 
the United States which 
are worked at present are 
in Missouri, Tennessee, and 
Kentucky. There are also 
deposits in Virginia and 
in Georgia, and _ large 
amounts are also found west of the Mississippi, but 
freight plays a very important rdéle in the shipping 
of barytes, and furthermore, only those mines nearest 
the surface can be worked at a profit. Barytes is not 
found in ledges or solid masses, but rather in isolated 
nodules. The pieces vary in size from an onion to a 
man’s head, and vary in weight from one ounce to 
twenty or twenty-five pounds. There are, of course, 
larger isolated lumps found, but generally speaking this 
is the manner in which the material is mined. The 
mining of barite, as a general rule, is simply done in an 





No. 56. AMERICAN BAryTES — Photo- 
micrograph x 380. 


II4 CHEMISTRY AND TECHNOLOGY OF PAINTS 


open cut, and much of the barytes found in the United 
States is associated with a material called “chirt,’’ which 
looks like barytes but can be very easily distinguished 
on account of its difference in weight. Chirt is a silicate 
of magnesia and alumina, and workmen very soon be- 
come adept in separating chirt from barite. Barite is 
usually contaminated with iron or with a sticky ferru- 
ginous clay, which can be separated by weathering or 
by washing. Some of the deposits in Virginia and 
Kentucky contain more than 1 per cent of lime and 
fluorine, which makes the ore undesirable for manu- 
facturing purposes but is not supposed to render it value- 
less as a paint base. To free it from iron it is bleached 
by what is known as the sulphuric acid process, but as 
it is generally washed, lixiviated, and floated after this 
treatment it is very seldom contaminated with any 
degree of acid. 


BARIUM SULPHATE (ARTIFICIAL) 


Synonym: Blanc Fixe, Lake Base, Permanent White; 
Specific Gravity, 4.1-4.2 

When a solution of chloride of barium is mixed with a 
solution of sulphate of soda a heavy white precipitate is 
formed which is known as artificial barium sulphate. 
In all of its chemical qualities it is identical with the 
barytes of nature, but in its physical qualities it is 
totally different. Depending somewhat on the method 
of its manufacture, the grain is exceedingly fine. 

Blanc Fixe has for years been used for the surface 
coating of paper, because when properly calendered it 
gives a very high polish and a permanent white surface. 
Originally it was a French product, the words ‘Blanc 
Fixe’? meaning ‘“‘permanent white.” In the early days 
of the paper industry various compounds of bismuth were 


THE INERT FILLERS AND EXTENDERS seb 





No. 57. COARSE AND FINE ParRTICLEs, No. 58. Branc FIxE, made of Carbonate 
GERMAN BarytTEes— Photomicrograph of Barium and Sulphuric Acid — Photo- 
X380. micrograph x4Io. 





No. 59. BLAnc FIxE, precipitated from No. 60. BLaNnc FIxer, made from Barium 
Barium Chloride — Photomicrograph 380. -  Sulphide— Photomicrograph x415. 


116 CHEMISTRY AND TECHNOLOGY OF PAINTS 


used for coating the paper. There are still visiting cards 
in existence which were surface-coated by means of bis- 
muth carbonate and bismuth subnitrate. These cards 
were readily affected by sulphur gases, and when it 
was found that precipitated barium sulphate produced 
an equally high glaze and the surface retained its pris- 
tine whiteness the name “Blanc Fixe” was universally 
adopted for the new product. 

In the paint industry it was recognized that pre- 
cipitated barium sulphate 
was a valuable adjunct in 
the manufacture of paint, 
owing to the fineness of 
the grain and other physi- 
cal characteristics of the 
material. It was found, 
however, that when it was 
dried and powdered it had 
lost its extreme fineness 
and did not mix readily ‘ 
with oil paints. In 1895 No.6r. BLANC Frxz — Photomicrograph 
Henry M. Toch succeeded x300. Precipitated from cold, dilute 
: ; ‘ barium chloride. 
in making Blanc Fixe, 
which, when dry, was a soft, impalpable powder of 
great value as a base upon which to precipitate lakes, 
and, likewise, when used in mixed paints and enamels 
imparted to them, under proper conditions, a vitreous 
surface which improved their wearing quality. To this 
product the name of Lake Base was given. A great 
many paint and chemical concerns have succeeded since 
then in producing Lake Base of a soft fine texture, and 
it has become one of the established bases of the paint 
trade. Its intrinsic value, when properly made, is about 
half that of American zinc oxid, but a number of writers 





THE INERT FILLERS AND EXTENDERS I17 


have erroneously stated that its body and covering 
capacity were equal to zinc oxid. Lake Base is success- 
fully used up to 70 per cent in white pigments, and in 
colored pigments up to 95 per cent. It is amorphous 
under the microscope, and is used to a great extent to 
increase the spreading of weaker or coarser colors. 

Since 1906 artificial barium sulphate or Blanc Fixe 
has been used by nearly every paint manufacturer in the 
United States, for its excellent qualities have been proved 
beyond a doubt. The value of this material as a reén- 
forcing pigment or filler in the manufacture of paints has 
been thoroughly demonstrated by the elaborate experi- 
ments made by the United States Navy, another indica- 
tion of how futile itis for any man to say without careful 
consideration what shall be regarded as an adulterant 
and what shall be regarded as a pure material. In 1910 
the Bureau of Construction and Repair of the United 
States Navy had come to the conclusion that the Bat- 
tleship Gray, which had been in use since the termina- 
tion of the Spanish-American war—a period of about 
ten years — did not give good results. The formula for 
the Battleship Gray as it then existed was practically 
45 per cent of white lead, 45 per cent of zinc oxid, and 
to per cent of lampblack. From the standpoint of purity 
this should be regarded as a very pure paint, and from 
all precedent it should be inferred that a paint of this 
type would be the best that could be made; but two 
things demonstrated themselves beyond peradventure. 
One was that such a paint was not hard enough to resist 
abrasion; furthermore, salt water in the form of spray 
or the water itself had a decidedly bad effect. When a 
paint of this type became wet it absorbed water, changed 
its color, and became very soft and spongy. The Navy 
officials most interested in this consulted the author, who 


118 CHEMISTRY AND TECHNOLOGY OF PAINTS 


devised a paint which then would probably have been 
condemned by painters in general. Previous experience, 
however, had taught that the addition of large quantities 
of artificial barium sulphate or Lake Base to a proper 
pigment improved the entire value of the paint, to say 
nothing of reducing its cost over 20 per cent. As a result 
the formula decided upon by the author was: 45 per 
cent of zinc oxid, 45 per cent of Blanc Fixe or Lake Base, 
and ro per cent of graphite and lampblack. The proper 
oils and driers were then added. A three months’ test 
was made on the machine repair ship “Panther,” and 
when this ship came back from a cruise it was found that 
the paint was sufficiently hard so that the anchor chains 
rubbing against the paint did not abrade it, and that 
the salt water, wherever it had wet the paint, did not 
produce any effect whatever. For upward of a year 
the Navy experimented in a small way painting other 
ships, until in 1915 as much as several hundred thousand 
pounds of Blanc Fixe had been bought by the Navy for 
the manufacture of Battleship Gray. There may come 
a time when a new paint superior to the present one 
will be devised, but this much has been absolutely proved | 
—that a mixture of 45 per cent of zinc and 45 per cent 
of Blanc Fixe for sea water purposes is far better than a 
similar mixture made of zinc and lead only. 

At the time the Navy formula was originated Blanc Fixe 
was worth about 2 cents per pound, which made a con- 
siderable saving to the Navy. At the present writing, 
owing to the European war and the fact that only one 
concern is at present manufacturing Blanc Fixe in the 
United States from American materials, and that the de- 
mand is great and the supply small, the price has risen 
to over $85 per ton. If the price should rise as high 
as zinc oxid or lead itself, it is quite obvious that in view 


THE INERT FILLERS AND EXTENDERS 119g 


of the purity of a paint made of Blanc Fixe the ques- 
tion of adulteration could not enter. It will therefore 
be seen that this question of adulterated pigments is all 
relative, depending entirely upon the results obtained and 
upon the cost of the material. 

As far as the influence of salt water on a paint made 
of Blanc Fixe is concerned, the writer had determined 
long ago that the action of sodium chloride (salt) in the 
air or in water is one of the causes of the chalking or 
decomposition of white 
lead. It must not be under- 
stood that the author is 
condemning white lead as 
a pigment. This is simply 
written to show that there 
are instances when other 
materials are better for a 
given purpose. 

Dry Blanc Fixe is des- 
tined to become .a very 
useful paint material. In 





No. 62. BLaNnc Frxe — Photomicrograph 
x300. Precipitated from hot, con- I905 there were probably 


centrated acid solution of barium not over 100~ tons per 


hloride. 
bya Veale ccd = I NeeLoloetne 


use had risen to over 3000 tons per year, because the 
textile manufacturers had also found that its use in 
materials like linoleum and table oilcloth not only saved 
in cost of manufacture over the higher priced pigments, 
but produced more flexible and lasting materials. The 
same can be said of the printing ink manufacturers, who 
today are as large consumers of dry Blanc Fixe as the 
paint manufacturers. 

As regards the manufacture of Blanc Fixe, this has 
also changed within the last ten years. Formerly it was 


120 CHEMISTRY AND TECHNOLOGY OF PAINTS 


known that only a solution of barium chloride and a 
soluble sulphate or sulphuric acid were the raw materials 
used for making this product, but today there are other 
methods which produce equally good materials, and in 
some instances better results than the chloride method. 
Tor instance, barium sulphide solution is precipitated 
with sodium sulphate, yielding a by-product, sodium 
sulphide, which can be sold at a considerable profit. 
The Blanc Fixe so made is denser than that made from 
the chloride. Blanc Fixe is also made from the peroxid 
of barium and sulphuric acid, but must be neutralized 
and freed from peroxid of barium before it is suitable for 
paint purposes. For certain color purposes the material 
is made from concentrated hot solutions, which produces a 
crystalline Blanc Fixe valuable for very brilliant colors, 
particularly greens and reds. Another method used is 
dissolving barium carbonate in nitric acid and _ precipi- 
tating with sulphate of soda, which then produces a Blanc 
Fixe equal to the chloride product. 

Blanc Fixe is made in various ways. For paint purposes, 
the usual method is to neutralize nitre cake with caustic 
soda or carbonate of soda which at the same time takes 
out all the iron, and add that to a solution of barium 
sulphide. This, when properly washed, gives a very fine 
and excellent Blanc Fixe. 7 

Another grade is a by-product from the manufacture 
of peroxide of hydrogen, and whereas it was formerly of 
a very poor quality, it is treated today by washing and 
by the continued addition of sulphuric acid, until it is 
perfectly neutral and of good quality. 

A third type of Blanc Fixe is manufactured very 
rapidly and exactly by taking freshly precipitated barium 
carbonate and mixing it with weak sulphuric acid using 
compressed air as a stirrer. By careful watching, Blanc 


THE INERT FILLERS AND EXTENDERS 121 


Fixe can be made which need not be washed, and which 
is absolutely neutral, but which will contain about one 
half to one per cent of unconverted barium carbonate. 
If just enough sulphuric acid is added so that no more 
CO, is liberated, when that point is reached not all of 
the barium carbonate has been acted upon, because some 
of it is occluded; there is sufficient barium carbonate present 
to take care of any excess sulphuric acid, and in that 
manner Angular, Crystalline Blanc Fixe is_ produced 
which is excellent for paint purposes. 

The microscopic form of Blanc Fixe made from barium 
carbonate usually varies with the strength of the sulphuric 
acid, but a very fine grade can always be made if the sul- 
phuric acid is sufficiently weak and the amount of water 
used as a diluent for the barium carbonate is sufficiently 
voluminous. 


BARIUM CARBONATE 
Formula, BaCO;; Specific Gravity, 4.2; Synonym, Durex White 


This material is practically new as a paint material, 
and has only come into use since flat wall paints have 
had such a tremendous success in the United States; 
and even at that, not very many manufacturers in the 
United States use it, although it probably is destined to 
become as useful an article as Blanc Fixe. | 

Barium carbonate, under the microscope, has a very 
peculiar structure. It is not made by mixing a solution 
of barium chloride and sodium carbonate, although that 
would be the normal way of making it, but it is made 
from barium sulphide and sodium carbonate in fairly 


122 CHEMISTRY AND TECHNOLOGY OF PAINTS 


concentrated solutions, so that the sodium sulphide be- 
comes a valuable by-product, and therefore the barium 
carbonate can be successfully marketed at a reasonable 
price. 

In hiding power it is between Blanc Fixe and zinc 
oxid, but when used in the proportion of 45 per cent 
barium carbonate and 45 per cent of zinc oxid or litho- 
pone in a flat wall paint its physical quality makes it 
particularly valuable, because the resulting paint with 
the proper thinners pro- 
duces a velvet finish unap- 
proached by anything else. 

Barium carbonate such 
as is sold for paint manu- 
facture must not be con- 
' founded with Witherite, 
the natural form of ba- 
rium carbonate. This is 
not found in the United 
States, but isms lareerm 
mined in England, Austria 
and Germany. Witherite 
has absolutely no paint 
qualifications, and is not even as good as_barytes. 
In composition Witherite is identical with the artificial 
barium carbonate, but under the microscope powdered 
Witherite is a transparent crystalline material similar in 
appearance to table salt. 





No. 63. BARIUM CARBONATE — Photo- 
micrograph x300. 


SILICA 
Formula, SiO.; Synonym, Infusorial Earth, Silex 


The introduction of silex in paint is due to the 
researches and investigations made by David E. Breninig, 
M.D., who in the early fifties had noted that when white 


THE INERT FILLERS AND EXTENDERS £28 


lead was mixed with barytes it stood exposure better 
than pure white lead. Late in the fifties he came across 
some rock crystal quartz, 
and, on grinding and mix- 
ing it with white lead, 
found that it improved 
the paint. The prepara- 
tion of silica, especially for 
the paint trade, became 
an established industry 
between 1865 and 1870. 
The earlier process for 
powdering quartz was the 
simple and _ economical 
method of dry grinding 
by the tumbling process. 
The quartz was simply crushed to a granulated state and 
then put into a tumbling barrel with pebbles, which was 
revolved until the silica 
was reduced to a compara- 
tively impalpable powder. 
It was found, however, 
that this method was not 
satisfactory, because it did 
not produce uniform re- 
sults, and the Silex Lead 
Company, which had been 
formed for the manufac- 
eB ture of silica or silex for 
No. 6s. Srr1ca — Photomicrograph X250, the paint trade prior to 
finely powdered and air floated, uniform = 870, adopted the process 
apegae Bran of heating the quartz to a 
visible red heat, plunging it into water, and crushing it after 
the sudden change of temperature had split the silica into 





No. 64. SILICA, OR SILEX— Photomicro- 
graph x250, very fine grain. 





124 CHEMISTRY AND TECHNOLOGY OF PAINTS 


a finer state of division. The silica was ground in 
tubs under water with stone bottoms and drag stones, 
and after it had been thoroughly comminuted it was 
washed, floated, dried, and then bolted to a given degree 
of fineness. There can be no question that the prepara- 
tion of silica in this manner produced a material of great 
uniformity, the value of which in paint is unquestioned. 
In the early part of the seventies the first practical tests 
were made on the coast of Maine. It was found that 
pure white lead would not 
stand exposure at the sea- 
shore for more than a year. 
At the end of this: timiess 
resembled whitewash and 
presented a poor surface 
for repainting. A mixture 
was made at that time of 
one third silica, prepared by 
heating and washing, one 
ae third zinc oxid, and one 
No. 65. SiL1cA— Photomicrograph x250, third white lead. These 
very fine grain; this material has been materials were ground to- 
ground in water. : ; . 
gether in pure linseed oil 
and sufficient drier added. At the end of seven years 
this paint was still in good condition and presented an 
excellent surface for repainting. 

Silica, like many of the inert materials, has the added: 
physical advantage of presenting what is known as a 
“tooth,” which fits it exceedingly well for repainting. 
Silica is Inert as an extender or filler in paint, and does 
not combine with any other pigment or vehicle. The 
detection of silica in mixed paints is very easily accom- 
plished by means of the microscope and Nicoll Prism, as 
the metallic pigments do not polarize. In chemical 





THE INERT FILLERS AND EXTENDERS Te5 


analyses we often find 1 per cent of silica in an otherwise 
pure paint. This 1 per cent of silica generally shows 
up in large arrow-head crystals scattered throughout 
the field of the microscopic vision, and is due _ to 
very small particles of silica which have been worn off 
from the grinding stones of the mill. The amount cf 
silica which may be safely added to many colored mixed 
paints without detracting from their covering properties, 
and which will increase their wearing qualities, is less 
than one third of the total pigments used. 

The composition of the various silicas on the market 
is quite uniform, and those which are made from clear 
colorless quartz, or faintly colored quartz, are practically 
free from iron. Silica made from rock quartz will assay 
99.7 S1QOs. 

Infusorial earth is almost pure silica and is largely 
composed of the skeletons of diatoms. It is exceed- 
ingly bulky, and is used by some paint manufacturers 
to prevent the settling or hardening of paint in cans, and 
owing to its light specific gravity it accomplishes this very 
well when added in even as small a quantity as to per 
cent. 

The question comes up occasionally as to whether 
silica will hydrate when heated and thrown into water. 
This question must forever be settled by the fact that 
analyses of silica treated in such a manner show it to 
contain 99 per cent SiO,. If any hydration took place 
it would be evident in the quantitative analysis. There 
can be no doubt that the silicas obtained on the market 
which are washed and treated are therefore pure SiQO.. 
The silicas made from infusorial earth contain a varying 
percentage of moisture, but the balance is almost pure 
silica. 


126 CHEMISTRY AND TECHNOLOGY OF PAINTS 


INFUSORIAL EARTH; KIESELGUHR; FULLER’S EARTH 


Infusorial Earth, Kieselguhr, and Fuller’s Earth are 
forms of silica which are diatomaceous in nature. Di- 
atoms are the remains of plant life—the silicious 
skeletons — the organic matter having been entirely de- 
composed, leaving these skeletons. The forms of these 
skeletons are wonderful, and a number of illustrations 
will show what they are like. Some are like beautiful 
chased jewels or filigree 
work; others are like the 
covers of boxes made of 
lace work; and still others 
are spear-shaped, but all 
of them have the quality 
more or less of absorbing 
dyes. They are not pure 
silica, for some of them 
are largely composed of 
silica and silicate of alu- 


— mina or silicate of mag- 
No. 67. KIESELGUHR, or INFUSORIAL 


EARTH— 300 Mesh, finely broken nesla. 
Diatomacae. These materials are 


used both as bases for the lake colors used in making 
pigments, and for the purpose of preventing the settling 
of certain classes of mixed paint, particularly the first 
coats which are not so finely ground. In this respect 
these materials are frequently substituted for asbestine, 
because they are more or less free from moisture or 
water in combination. ‘They can be readily identified 
under the microscope on account of their very peculiar 
and beautiful forms. 





THE INERT FILLERS AND EXTENDERS 127 


CLAY 
Composition, Silicate of Alumina; Synonym, Kaolin, Fuller’s Earth 


Clay in small quantities is very largely used by paint 
manufacturers, first, to prevent settling or hardening 
of mixed paints, and sec- 
ondly, to produce unctu- 
ousness or good brushing 
quality. Clay occurs natu- 
rally in many paints up to 
as high as 80 per cent, as 
for instance, ochre, which 
is 80 per cent of clay and 
Gamepet. cent .o1 coloring 
matter. The siennas all 
contain clay up to as high . 
as 60 pen, “cent, and aS No. 68. Diatoms — Photomicrograph 
clay is found naturally in X 500, found in whiting, clay, and 
the pigments referred to Bie 
they cannot, of course, be regarded as adulterated, but 
| when large quantities of 
clay are added to other- 
wise good paints the wear- 
ing quality is reduced, and 
therefore more than to or 
I5 per cent is not advis- 
able. Clay always contains 
a large percentage of water, 
and the emulsification that 
ensues probably aids in the 
non-hardening qualities of 
No. 69. Diatoms — Photomicrograph paint. In paste paints of 

x600, frequently found in whiting. j 
the cheaper variety, par- 


ticularly barrel paints, clay becomes a necessity, for these 








128 CHEMISTRY AND TECHNOLOGY OF PAINTS 


paints are sold at a very low price, and must remain 
soft indefinitely and easy to mix. 

Kaolin is a type of clay which is used by the pottery 
trade; a typical analysis is as follows:! 


yO MTR RN Ge Ser) re este 46.27% 
AlsOg? sath Aid ss on ak eee ee 20.576 
F603 (51. OM i oe ee 1.30% 
CaO pF ri Oe ee eee eee ey As 
MgO... ee ae 0.25% 
KO. 0) ee eee eee ee O29, 
Na,O ogden 5 ERE OR. ono, RIO Booch a OF4 7 We 
HoOe es cae fe ee ee rO0 

IOI.00% 


It has practically the same physical value as the 
ordinary clay, excepting that the pottery clay is usually 
whiter in color. Clay has 
no hiding power or opacity. 
Kaolinite, 2SiO.2 - Al,Os3 - 
2H.0, is the principal con- 
stituent of kaolin. 


ASBESTINE AND ASBESTOS 


Asbestine and asbestos 
are silicates of magnesia, 
asbestine having a short 
fibre and asbestos having 
a long fibre. 

Asbestos fibre is used 
to a small extent in paint, but it is not as good as 
asbestine, because the fibre of asbestos is too long. 
However, considerable quantities of asbestos are used 
for the making of so-called “‘fire-proof” paints, and on 
this subject it is proper to say that there is no such 





No. 70. CLay— Photomicrograph x300. 


1 Bull. 351 (U.S. Geol. Surv.), Clays of Arkansas, p. 21. 


THE INERT FILLERS AND EXTENDERS 129 


thing at the present time as ‘“‘fire-proof” paint. It 
is perfectly possible to make a fire-resisting paint, but 
these paints usually are 
of the casein-whiting type. 
Casein, lime, phosphate of 
soda, and whiting, which 
when mixed with water 
produce fairly good kalso- 
mine, resist fire for a little 
while. A typical experiment 
has always been to take a 
small shingle, paint half of 
it with a so-called “fire- 
proof” Da and ignite No. 71. Curya Cray— Photomicrograph 
the uncoated part; the fire ho 

dies out when it reaches the painted part. This can 
be done with a piece of wood from ;’s to 4 inch in 
thickness, but no timber or board of any size can pos- 
sibly be rendered fire-proof 
by paint application, for 
when such a piece of wood 
| or timber is subjected to 
sufficient heat, distillation 
of the uncoated wood on 
the inside takes place, gas 
is generated, and the wood 
bursts into flame. The only 
successful method of treat- 
ing wood to prevent it from 
burning is by impregnat- 
ing with alum salts by 
means of a vacuum pro- 
cess; but this is not painting, because the crystallizing 
effects of the fire-proofing material destroy or peel 








No. 72. COLLOIDAL Clay — Photomicro- 
graph x300. 


130 CHEMISTRY AND TECHNOLOGY OF PAINTS 


any subsequent paint or 
varnish, so that up to now 
there has been no fire-proof 
paint made which renders 
wood structures fireproof. 

For the painting of shin- 
gles where sparks may pos- 
sibly ignite them, oil paints 
containing boracic acid and 
powdered asbestos are used, 
as a paint of this type resists 
Se. sparks. 

No. 73. TYPICAL ASBESTINE X180. Asbestoscan bevery read- 
ily identified under the mi- 
croscope on account of its 
long fibre. The average 
analysis of asbestine is: 





S10. Te oO cae Oa, See era ee 62 Wi 
MoO wis Sere teem at % 
(Cat) ten o G Nain to ieee 20, 


Water of Crystallization 4% 
1cO”%, 


CaLcIumM CARBONATE 
Formula, CaCO; 
Synonyms: Whiting, Paris White, 
Chalk, Marble Dust, Artificial vs a 
Calcium Carbonate, Spanish No. 74. PRECIPITATED CHALK, ground 
White, and White Mineral Primer in Roller Mill—Photomicrograph x 280. 





Whiting and natural calclum carbonate are prepared 
from the natural chalk deposits of the cliffs in the south 
of England, and Paris White, Extra Gilder’s White, and 
Spanish White are all different qualities of whiting de- 
pending on the amount of levigation and fineness of grain. 
The mode of preparation is very simple. It consists in 
grinding the cliffstone in water, washing it, and allowing 


THE VINERT -FILLERS- AND “EXTENDERS TAL 


it to settle in large vats. The cream, or that. which is 
nearest the surface, is dried over steam-pipes, bolted, and 
sold as Paris White. The 
next layers are sold under 
the name of Extra Gilder’s 
White, and the bottom 
layer as Commercial White, 
of which putty is made. 
Whiting is a neutral calcium 
Carbonate, and . with . the 
exception of the small per- 
centage of water, which is 
very variable and depends ' 
upon how thoroughly it has No. 75. Wuirine oe Photomicrograph 
been dried, it is remark- Soe ee ae 
ably pure and fine. The material at the bottom of the 
tubs known as Commercial Whiting is never used in 
the manufacture of mixed paint, because it is coarse, 
contains silica and iron, 
and in attempting to grind 
this grade the mills are 
ruined. 

There is a great differ- 
ence of opinion as to the 
merits of whiting in paint, 
but it will be conceded 
by. every manufacturer 
and paint chemist that 
the addition of calcium 
carbonate in some form 
or other is of great benefit 
to mixed paint. Some 
manufacturers put 5 per cent in all the paint they make, 
excepting that which is made according to specification, 








No. 76. GILDER’s WuitiInc— Photomi- 
crograph x300, 


132 CHEMISTRY AND TECHNOLOGY OF PAINTS 


for the excellent reason that any acid which may either 
develop in the paint or be a part of the chemical com- 
position of the paint is 
slowly neutralized. For 
paints intended for the 
protection of metal this 
practice is to be highly 
recommended. On_ the 
other hand, some writers, 
«. who, however, have had 
7 - little or no practical ex- 
perience, condemn calcium 
carbonate in any form be- 
cause it lacks covering 
capacity or hiding power. 
If a paint were made of 
roo per cent calcium carbonate this statement would 
hold true, but where other solid pigments are added 
the argument against whiting fails. No particular evi- 
dence need be brought to 
bear to prove the durability 
of whiting, for the reason 
that all putty is made of 
whiting and oil, and there 
are buildings and farm- 
houses in any number still 
existing where the putty, 
after being exposed to the 
elements anywhere from ; 
twenty-five to seventy-five - 

years, is, if anything, better INO va: Tate (Soapstone) — Photo- 
at the end of that period image 

than one month after it was applied. Whiting has the 
added advantage of being bulky, and priming coats in 





No. 77. CALtcruM CARBONATE (artificial) 
— Photomicrograph 300. 





THE INERT FILLERS AND EXTENDERS 133 


which it is used present a good surface for repainting. 
The amount that can be used as an assistant to mixed 
paint is very variable, de- 
pending largely on the pig- 
ments used or shade which 
is made. Where a paint 
is to be made for the in- 
terior of a building in 
which acid fumes are gen- 
erated whiting should, of 
course, be omitted. But 
there are so many excel- 
lent fillers that the use of at 
a single one is not always No. 79. Basic Macnesri CARBONATE 
necessary. Whiting Ast — Photomicrograph x300. Extremely 
: : light and fluffy. 

is made today is never 

alkaline, for in the drying process it is placed on steam- 
pipes and the temperature is so low that decomposition 
cannot take place. 

The other forms of cal- 
clum carbonate which are 
in use are produced by 
. grinding white marble very 
* fine, and, generally speak- 
*- ing, these varieties are 
better for mixed paint 
purposes than whiting 
made from chalk.) In 
the first place, ground 
marble and limestone con- 

base for printing ink colors—Photo- tajn little or no moisture; 

eee: in the second place, they 
are ground exceedingly fine, and being angular or crys- 
talline in shape they form a better surface. if anything, 








134 CHEMISTRY AND TECHNOLOGY OF PAINTS 


for repainting than whiting; and third, where an absolute 
chemical composition is wanted they produce more uni- 
form chemical compounds. Whiting and white filler 
compounds bulk between 3% and 4% gallons per hundred 
pounds of dry unit. 

There is another grade of calcium carbonate which 
occasionally appears on the market and is a by-product, 
principally from soap works. It has all the physical 
characteristics of a good article, but its chemical char- 
acteristics condemn it at once as a paint material on 
account of the free lime which it contains. It is worth- 
less for the purpose of making putty and useless as a 
paint filler. When putty is made of it, it forms a lime 
soap and gelatinizes the contents of the packages. 


WHITE MINERAL PRIMER 


This is a white crystalline limestone which is found 
chiefly west of the Mississippi, and more largely used by 
western paint manufacturers than by eastern, for the 
freight is against its shipment to eastern points. 

In physical structure it is similar to barytes, but of 
much lighter gravity and greater bulk. For instance, 
too pounds of white mineral primer will yield 4.6 gallons, 
while 100 pounds of barytes will yield 2? gallons. White 
mineral primer has very little opacity or hiding power, 
but it has the physical quality of “‘tooth,’ and when 
mixed with zinc or sublimed lead it is superior to any 
other form of whiting, with perhaps the exception of the 
artificial calclum carbonate. In many respects it is similar 
to finely powdered marble dust. 


MARBLE DUST 


Considerable marble dust is used in certain forms of 
paint, marble dust being chiefly composed of calcium 


THE INERT FILLERS AND EXTENDERS 135 


and magnesium carbonate with 1 or 2 per cent of 
ferric oxid. It is a brilliant white, and when passed 
through a screen of 200 mesh is similar to white mineral 
primer. Its chief use is for carriage and coach paints 
and also as a primer for wood generally, because it pre- 
vents peeling on account of its structure, having the 
same properties of ‘‘tooth’”’ which are ascribed to silica 
and white mineral primer. 


SPANISH WHITE 


Spanish White is similar in all respects to powdered 
chalk, Paris White, or whiting, and at the present time 
is a name only, for there is little or no whiting for paint 
purposes that is now imported from Spain, all of it being 
of the cliffstone variety from England. 


ARTIFICIAL CALCIUM CARBONATE 


This material has already been referred to. It has 
very excellent properties, but usually has the one great 
defect, viz. the small percentage of free alkali both 
of lime and soda which it contains, and this produces 
‘“livering’’ of paints. Wherever it can be obtained in 
neutral form it is excellent when added in small quan- 
tities to many priming paints. 


GYPSUM _ | 
Formula, CaSO,+ 2H2O 


As an inert pigment or filler gypsum is very largely 
used in the United States. It is found in twelve states 
and in very large quantities in Canada. Its specific 
gravity is 2.5 and its formula as cited above is CaSO, 
plus 2H.0. This formula represents the gypsum of 
~ commerce, as sold to the paint trade, so closely that the 


136 CHEMISTRY AND TECHNOLOGY OF PAINTS 


percentage of water in several samples averaged over 19, 
whereas the theoretical is 20.2. 





No. 81. AMERICAN Gypsum — Photo- No. 82. AMERICAN Gypsum — Photo- 
micrograph  X250, fairly uniform micrograph X300, transparent flat 
and flat crystals. crystals. 


There is a great difference of opinion as to the merits 
of gypsum as a paint filler, for it must be borne in mind 





No. 83. AMERICAN TERRA ALBA— Pho- No. 84. Catcrum SuLpHATE (Gypsum) 


tomicrograph 250, very finely pow- — Photomicrograph x250 (Ameri- 
dered. can). 


that if it contains any free lime, or if it is not fully 
hydrated, the lime will act injuriously on the paint and 


THE ‘INERT FILLERS AND EXTENDERS 1237 


thicken it unduly. The defect produced by its incom- 
plete hydration will be to take up moisture from other 





No. 86. TerrA ALBA (French Gypsum) — 
Photomicrograph 600, showing crys- 
talline structure of calcium sulphate. 


No. 85. FRENCH TERRA ALBA.— Pho- 
tomicrograph 250, composition 
CaSO, + 2 H2O, same as gypsum. 


materials in the paint so that a hardening or setting 


process goes slowly on. 





No. 88. PRECIPITATED CALCIUM SUL- 
PHATE — Photomicrograph x300. Note 
the long-fibred crystalline structure. 


No. 87. Catctum SULPHATE — Photo- 
micrograph x300. Ppted. from cold, 
moderately concentrated solutions. 

Some of the gypsum sold in the east is made from 
alabaster, this being a native, translucent calcium sul- 


138 CHEMISTRY AND TECHNOLOGY OF PAINTS 


phate. The Pennsylvania Railroad in its freight car 
color permits the use of 70 per cent of gypsum, and as 
good results have been obtained by this company in the 
use of calcium sulphate as a filler the condemnation of 
this material is without much foundation. Due con- 
sideration must be given to the fact that thousands of 





No. 88a. CHROME GREEN 25%, BARYTES 75 %.— Photomicrograph 
X380. Photograph distinctly shows the crystals of Barytes, some of 
which are very fine. 

tons of Venetian red are consumed by the paint industry 
every year, and that the composition of Venetian red 
will average from 15 to 4o per cent ferric oxid, the 
balance being entirely gypsum. It is nevertheless true 
that as one part of gypsum is soluble in five hundred 
parts of water, excessive rainfall will erode it in a paint, 
particularly where the binder is easily attacked. 


THEO INERT FILLERS AND EXTENDERS 139 


Where calcium chloride is a by-product large quan- 
tities of calcium sulphate are artificially made, and many 
paint manufacturers prefer the artificial calcium sul- 
phate to the natural. The photomicrograph shows this 
to have a long-fibred crystalline structure, and while 
it has no chemical properties which are different from 
the natural gypsum, its purity and physical structure 
make it valuable for many mixed paint purposes. 


CHA BUH hee 


LAKES. AND TONERS) 


Lakes may be considered as being white or colorless 
bodies dyed with an organic coloring matter, formerly 
natural vegetable and animal dyestuffs, now, with few 
exceptions, all aniline or coal tar dyes. 

Some of the principal bases used are barytes, aluminum 
hydrate, Blanc Fixe, clay, whiting, etc. They are made 
into a paste with water and the dye solution is added. A 
salt or acid is then added which precipitates the dye on 
the base in an intimate mixture. 

Sometimes the base reacts with the dye to form a new 
material by chemical reaction or by absorption; more 
often the base is inert and is merely dyed by the coloring 
matter. With some dyes a mordant or developer is needed 
before the color is produced. Depending on the chemical 
nature of the dye used, and on the shade desired in the 
finished lake, various precipitants are used. 

Toners are precipitates of the dye as a dye salt, and 
contain no base. They have naturally much more tinc- 
torial power and purity of shade. 


PROPERTIES OF LAKES AND TONERS: 


Generally speaking, although there are exceptions to 
these statements, the lake colors are more brilliant and 
have clearer, cleaner tones than the other pigments. They 
are not among the more permanent colors, many of them 
being extremely fugitive, and only a very few of them being 
really permanent. Lakes made on an Aluminum Hydrate 


140 


LAKES AND TONERS I4I 


base are transparent and are used in the printing ink trade. 
Those on Blanc Fixe are used in paint, and for most of 
the other purposes. 

RED LAKES 


Red lakes and toners are the most important of the 
inorganic or lake colors, because they comprise all the bright 
reds that are used. With the exception of Mercury Ver- 
milion, a very expensive color and unfit for many uses, 
there are no bright reds in the inorganic or mineral class 
of colors. 

Among the most important of these reds is the follow- 
ing group of toners and lakes made directly from the 
intermediate salts and acids, that is, the coloring matter 
is produced and the insoluble pigment made during the 
same process of manufacture. 


PARANITRANILINE REDS 


Paranitraniline or “Para Toners” are strong bright 
reds of a fair degree of permanence. They are seldom made 
into lakes, for when compared with other organic reds their 
undertones are brownish and not clear. They are gen- 
erally found on the market in two distinct shades, light 
and deep. The following outline of their manuiacture 
will show the reactions involved. 

Paranitraniline (CsHsNH2NO:, brownish crystals in- 
soluble in water) is changed to the soluble hydrochloride 
by boiling with HCl. It is then diazotized with sodium 
nitrite substituting, as will be seen, a diazo group (N:N) 
for the amido group (NH). | 

C,Hi-NO.-NH2 + 2HCl = CeHy: NO2: NHe- 2HCl 
Paranitraniline Paranitraniline hydrochloride 
C.Hu- NO. NH2: 2HCl + NaNO, = CysHu:NO.-N-NCl 

This reaction, diazotization, is the basis of the manu- 

facture of a large number of lake colors; diazotizing an 


142 CHEMISTRY AND TECHNOLOGY OF PAINTS 


amido compound and coupling it with a naphthol or phenol 
compound. 

When the diazo mixture has been made it is run into 
the beta naphthol solution forming the toner, or if a base 
has been added, the lake. The reaction must be made 
at a low temperature, usually 5° C.-1o° C. as the mixtures 
decompose at higher temperatures. This is generally the 
case in all-.diazotized fsroducts. 


Beta Naphthol Solution: 
Ci9H,0H a NaOH = C,)H;ONa + H.O 
(Beta Naphthol) (Sodium Beta 
Naphtholate) 


Coupling reaction: 


C,H4: NOo: N : NCl + CiyH7ONa == CeHa: N NC,H;OH + NaCl 
(Para Red) 


Various salts are added to produce different shades; 
monosulphonic acid will produce a deep shade. 

Para toners are fairly stable, but are not to be con- 
sidered as permanent colors; they fade or tend to darken 
on long exposure to light and have the undesirable proper- 
ties of “bleeding” and “striking through.” 


TOLUIDINE TONER 


This color is one of the more permanent reds. It has 
a very bright fiery shade but like para, has a rather brown- 
ish undertone and is seldom used as a lake, although expert 
manufacturers are able to produce toluidines with a fairly 
clear bluish undertone. One shade only, is generally offered, 
softness of texture and purity of tone are the properties 
to be watched. 

Its process of manufacture is analagous to paranitrani- 
line reds, meta nitro ortho toluidine being the nitro com- 
pound used. 


LAKES AND TONERS 143 


LItHoL RED 


Unlike the two foregoing examples, this color has a 
fairly clear, bluish undertone and is principally made in 
lakes of varying strength. As regards permanence, it is 
approximately the same as toluidine. The majority of 
color makers prepare this from Lithol Red dye, but the 
larger manufacturers make it direct from the intermediates. 

The soluble dye which is on the market in paste form 
is the sodium salt. By boiling with barium chloride, cal- 
cium chloride or other salts, a number of shades of insoluble 
toners and lakes may be obtained. 


MADDER OR. ALIZARIN LAKE 


Madder lake is unique among the organic pigments in 
that it is an absolutely permanent color, ranking in this re- 
spect with the most permanent metallic oxids and earths. 

The madder lakes were originally made from the root of 
the madder plant, but since 1868 synthetic alizarin, which 
produces lakes, equal in every respect to those made from 
the vegetable product, has been made on a large scale. 

Alizarin, Cy,H,O.(OH). or dioxyanthraquinone is a 
yellow crystalline substance, insoluble in water, and so 
difficult to wet that it is sold as a 20 per cent paste. Many 
shades of lakes ranging from a deep bluish maroon to a 
bright scarlet, all having a characteristic bluish under- 
tone, may be made, and a number of formulas and methods 
have been recommended. 

For the most desired shades, the light reds, the best 
results are obtained by mixing the alizarine paste with a 
freshly made washed alumina hydrate base and adding 
calcium chloride, sodium phosphate, and Turkey red oil 
(a sulphonated castor oil) in proper amounts. 

Upon boiling, the color of the mixture gradually turns 


144 CHEMISTRY AND TECHNOLOGY OF PAINTS 


red and after 8 to 1o hours boiling it is fully developed. 
Considerable expert manipulation is necessary to make good 
alizarin lakes and only the most expert color makers 
can produce uniform products of good quality. Minute 
amounts of metallic impurities, particularly iron will spoil 
the shade of an otherwise well-made alizarin lake. 


OTHER RED LAKES 


Scarlet 2R, Ponceau R, and the other scarlet and 
red Azo colors are used to make lakes which are not being 
used as much as formerly, owing to the development of 
more permanent reds. Most of them are precipitated 
with barium chloride. 3 

Imitation vermilion is generally made by precipitating 
eosine with lead acetate on a base of orange mineral or 
white lead. Eosine and colors allied to it, viz., phloxine, 
rhodamine, etc., are used to produce such colors as gera- 
nium, bronze red, rose bengal and delicate shades of 
pink. They are extremely fugitive and are only used when 
their exact: shades cannot be duplicated. Recently, 
patented colors of greater permanence have been offered 
as substitutes for these products. 

Maroon lakes are used in the manufacture of coach 
colors and are made from a number of aniline dyestuffs. 
Hypernic or logwood extract is still used to some extent, 
but there are at present several maroons of good perma- 
nence on the market. Hypernic maroon and alizarine are 
the two colors generally blended with or precipitated on 
an iron oxide base to make Tuscan red. 


OTHER LAKES 


Orange, yellow, green, blue, and violet lakes are of 
little interest to the paint manufacturer except the “lime- 
proof’’ lakes which are fast to alkalis, and are used in 


LAKES. AND TONERS 145 


paints having an alkaline medium or over surfaces which 
are likely to have an alkaline reaction on the film. The 
other lakes are mainly used in printing inks. 


O1L SOLUBLE COLORS 


Colors which are soluble in oils, fats, oily solvents and 
spirits are used for a large number of industries, such as 
the manufacture of transparent stains, candles, rubber 
driiclcsmpyroxyin, etc.» Some of them are true aniline 
dyestuffs, mainly the Azo colors from which the sulphonic 
acid group is absent, and they are fast to light. Others are 
merely precipitates of basic dyestuffs with salts of fatty 
acids, resinates, oleates or stearates. These basic colors 
are fugitive but are used where fast oil colors cannot be 
had in the proper shades. 


LIBRARY __ 


PATENT AND DEVELOPMENT DEPT. 


SINCLAIR REFINING COMPANY. 


~ 


' Section 


DR SM an aT Om eI 


CHAPTER XII 
MIxeEp PAINTS 


WE have seen from the foregoing chapters the ma- 
chinery necessary for the manufacture of mixed paints 
and the raw materials most generally used. 

Of all the shades of mixed paints made, the white 
paints are the weakest and perish the most quickly, and 
the black paints, particularly those high in carbon and 
the ferric oxids, are those which last the longest. . It is, 
for instance, impossible to state which of the white paints 
is the best, and individual opinions or single instances 
are not permissible for comparison. A test of white 
lead at the seashore will show that white lead is not 
as good as other white pigments, and at the same time, 
in a test in the interior of the country, or where climatic 
changes are not generally marked, white lead will show 
up wonderfully well. As an instance of this, it may be 
cited that the United States Light House Department 
ordered their white mixed paint to be composed of 75 
per cent zinc oxid and 25 per cent white lead) format tie 
seashore this mixture is better than either pigment alone. 

A series of experiments conducted by the author 
showed that white lead perishes through the action of 
carbon dioxid in rain water. As soon as a film of oil 
becomes vulnerable the white lead becomes soluble in 
the rain water, the so-called chalking being traceable 
to this cause. Zinc oxid is also attacked by carbon 
dioxid, but not nearly as quickly as white lead. Sub- 


limed white lead is attacked still less than zinc oxid and 
146 


MIXED PAINTS 147 


zinc lead. The western zincs and leaded zincs, which 
vary in their proportion of lead sulphate, are slightly 
more permanent than zinc oxid, but the moment an inert 
filler such as barium sulphate, either precipitated or 
natural, silica or magnesium silicate, are added to the 
white lead and zinc oxid paints, their resistance to atmos- 
pheric influence is largely increased. Therefore these inert 
materials are an improvement to paint, and where no 
specification is to be followed they cannot be regarded 
as adulterants. The principal reason why these inert 
fillers are not added in greater quantities to white paints 
is due to the fact that the consuming public is not yet 
sufficiently educated to the use of such materials. 
Lithopone has proved itself an extremely valuable pig- 
ment, particularly for floor paints and for marine 
paints where shades other than white are demanded. 
In no sense can the 7o per cent of barium sulphate 
which is contained in lithopone be regarded as an adul- 
terant, because it is a constituent of the paint itself. 

The carbon and graphite paints have wonderful 
powers of resistance, provided they are properly diluted 
with a heavier pigment so that the film is thicker. 
The average graphite paint will cover one thousand square 
feet to the gallon, but the film produced is so thin that 
when it once starts to go, either through the abrasive 
influence of the solid contents of the atmosphere or the 
decomposing action of water, the surface is soon exposed; 
but when many successive coats are applied to produce a 
sufficient thickness far better results are obtained. 

The ferric oxid paints strike a happy medium, for 
they cover from four to six hundred square feet to the 
gallon; but their color is limited to three shades — red, 
brown, and black. As priming and second coats they 
are, however, ideal, and as finishing coats where 


148 CHEMISTRY AND TECHNOLOGY OF PAINTS 


these shades are admissible they serve their purpose 
exceedingly well. 

No single pigment is as good as a mixture of pigments, 
and the intelligent combination of the raw materials 
always produces the best results. 

There is continued rivalry between the manufacturers 
of the lead pigments and the manufacturers of the zinc 
pigments, both of whom claim superiority for their 
particular pigments. If you read the advertisements in 
any of the weekly journals or in the paint magazines 
you will see after reading one advertisement that only 
white lead is the best pigment, and after reading another 
advertisement that only zinc oxid is the best pigment; 
but competent investigators who are more or less honest 
hesitate to say that zinc oxid is better than lead, or 
that white lead is better than any other pigment. As a 
matter of fact, it is a very difficult thing to decide; 
a just decision would be that they are all excellent. 
White lead, of course, stands supreme for hiding power. 
There is no pigment with the exception of lithopone that 
will show as much opacity as a single coat of white lead. 
On the other hand, there is no material that has such 
wonderful qualifications for enamel-making as zinc oxid, 
and, as a matter of fact, the only single pigment that can 
be used and is used for certain purposes is zinc oxid, all 
the others being unsuited for the manufacture of prepared 
paints on account of their gravity. It has been con- 
tended that white lead alone mixed with the proper oil 
and driers has stood for many years, and this is quite 
true; but zinc oxid alone, as a pigment at the seashore, 
does not give as good results as white lead, because zinc 
oxid dries too hard; and yet, from the large experiments 
made by the author, a mixture of the two is unques- 
tionably better than any single pigment, although 


MIXED PAINTS 149 


failures of mixtures are perhaps as frequent as failures of 
single pigments. 

That mixed paints have become a necessity is evi- 
denced by the fact that considerably more than one 
hundred million gallons have been made in the United 
States since 1907. The exact amount made at the pres- 
ent time is very difficult to determine, but it has been 
estimated as being over one hundred fifty million gallons. 
At the same time, the production of lead has increased, 
and the production of zinc pigments likewise. Likewise, 
the production of both the sublimed white lead and of 
the sublimed zinc and lead of the Ozark type are increas- 
ing, and have come to stay, so that the criticisms of the 
various pigments are more or less a question of com- 
mercial rivalry rather than an inherent defect in any 
of the pigments. They all serve an excellent purpose 
and all are exceedingly useful. 

Many manufacturers of mixed paints guarantee that 
their paints will stand five years under ordinary con- 
ditions in the United States. This guaranty is prob- 
ably excessive, for there are many details which on 
their face appear insignificant and are not taken into 
-account by a manufacturer. 

The priming of wood has much to do with the life 
of paint, and a paint that contains much oil or vehicle 
to which either pine oil or benzol has been added, 
so that penetration into the wood can be effected, will 
give much better results than very heavy paints con- 
taining only 40 per cent of vehicle and 60 per cent of 
solids. For the priming of wood this proportion should 
be reversed and the paint should contain at least 60 
per cent of liquids and 4o per cent of solids, to which for 
raw new surfaces a penetrative solvent like benzol, toluol, 
or pine oil should be added. 


150 CHEMISTRY AND TECHNOLOGY OF PAINTS 


On the other hand, the oxid of iron paints such as 
Princess Mineral or Prince’s Metallic have been known to 
last twenty years on wooden barns in the country dis- . 
tricts; this is undoubtedly due to the fact that a reduced 
oxid of iron of the Prince’s Metallic type is not affected 
by gases, nor does it react on linoxyn. As cottages, 
villas, and private residences are never painted a dark 
brown or a deep red like any one of the ferric oxic com- 
binations, it is therefore proper that this discussion relate 
entirely to the lead and zinc pigments which are most 
largely used for the purposes mentioned. 


ANTI-FOULING AND SHIP’s BOTTOM PAINTS 


Anti-fouling and ship’s bottom paints are always 
sold ready for use, and there are two distinct types,— 
the copper paints and the mercury paints. 

There is a continual difference of opinion among both 
consumers and manufacturers as to whether the anti- 
fouling type of paint should be one that does not dry and 
be of the exfoliating type, which means that it contains 
lard or tallow and that when the barnacle or seaweed 
attaches itself it drops off by its own weight, or whether 
the paint should be of the poisonous type, so that when 
the barnacle or submerged growth has absorbed a suf- 
ficient quantity of the poison it dies and drops off. 
This is a much mooted question, and there is much to 
be said on both sides. Naval Constructor Henry Wil- 
liams of the United States Navy has probably done more 
work on this subject for the American Navy than anyone 
else, and his type of paint which contains the red oxid 
of mercury has undoubtedly given far better results than 
any other anti-fouling paint. The composition of the 
paint used by the United States Navy is as follows: 


MIXED PAINTS IST 


> Sa NY ANTI-FOULING PAINT 
65 gals. Shellac Varn. 15 lbs. Zinc Oxid 
4 


Gee en Alc: Slee Blancsbhixe 
Pete eee aie Lar 25 ‘‘ Indian Red 
fae el urps, — 10 “© Red Oxid Mercury 
Yield : T5 gals. 


The copper paints which are found on the market con- 
tain from to percent copper scale (copper oxid — Cu,.0) 
to as high as 4o per cent. As a rule, this is added in a 
very fine powder to a mixture of linseed oil, pine tar, 
benzol or gas house liquor, and oxid of iron in some form, 
usually of the Prince’s Metallic type, is added as a 
pigment for hiding power. This is a so-called red or 
brown copper paint. The green anti-fouling is generally 
a copper soap manufactured by saponifying either linseed 
oil, tallow or fish oil with caustic soda, and then adding 
sulphate of copper to this soap, which produces an oleate 
or linoleate of copper and sulphate of soda as a by-product. 
The sulphate of soda is washed out, the remaining water 
boiled off, and then pine tar and linseed oil added to the 
mixture together with chrome yellow and Prussian blue 
for hiding power. This yields a semi-drying or non- 
drying type of green anti-fouling, which in many instances 
has given excellent results, but which in some tropical 
waters does not show up as well as the oxid of copper 
paint. The copper paints do not show up as well as the 
mercury paints. : 

There is a third type which is not a paint, but which 
is really a soap that is applied hot. Oleate or linoleate 
of copper mixed with China wood oil when melted and 
applied to a thickness of about 4's to § of an inch has 
given very good results, and it is stated that this type 
of copper paint is a happy medium and possesses both the 
exfoliating and the poisonous qualities so much in demand. 


152 CHEMISTRY AND TECHNOLOGY OF PAINTS 


CONCRETE OR PORTLAND CEMENT PAINTS 


Portland cement is an alkaline rock-like substance, 
which after it has set liberates lime. The literature is 
replete with statements that Portland cement floors 
cannot be painted, and it was not until 1903 that the 
first successful experiments were made for the painting 
of Portland cement. Prior to that time all sorts of 
things were recommended, such as strong acids like 
sulphuric acid and acetic acid, but it was soon found 
that the application of acids of this type to Portland 
cement destroyed the Portland cement because it dis- 
solved out the lime and left the sand and aggregate 
loosely bound. 

Portland cement floors “‘dust”’ up under the abrasion 
of the heel, and until a successful method for painting 
them was found it was impossible to use them in an 
uncovered condition. In power houses where delicate 
electrical machinery was placed the contact points were 
ground out by the silicious matter floating in the air 
through abrasion of concrete under the feet. The ac- 
companying photomicrographs show the appearance of 
a Portland cement floor highly magnified, and indicate 
in a general way the necessity for painting Portland 
cement. In warehouses, storerooms and offices generally, 
concrete floors. had to be covered with linoleum or wood 
to prevent this continual dusting, which became obnoxious. 
The paints made of drying oils were readily saponified 
and gave unsightly effects, and it was not until the 
publication of a patent on this subject (U. S. Letters 
Patent No. 813,841) that the trade in general began to 
understand that a resin acid was necessary to combine 
the lime and not destroy it. Previous attempts had 
been made depending upon the destruction of the lime, 


MIXED PAINTS 153 


but in this patent it was first shown that a chemical 
reaction took place and the lime instead of being de- 
stroyed was made to serve a useful purpose. A resinate 
of lime was formed when the coating applied had a 
sufficient acid number. 

The amount of free lime in concrete is not very 
great, for in a 1:3 mixture, that is, a mixture containing 
one part of cement and three parts of sand, the top sur- 
face varies in composition from 0.87 to 1.6 per cent of 
free lime. A large number 
of analyses were made by 
the author, and it became 
obvious that an acid num- 
ber of 5.0 is sufficient to 
more than neutralize the 
amount of lime present, 
and once neutralized dust- 
ing does not take place. 
It is well known that con- - 
crete of any kind and of . ee. 
any mixture is rapidly No. &. Photomicrograph of Portland 


disintegrated by paraffin cement floor composed of 2 parts sand 
7 and 1 part cement. This floor is po- 





or machinery oils and re- rous and will disintegrate rapidly unless 
duced in time. 3 Ee how- properly treated with a cement floor 
paint. 


ever, the cement filler or 
neutralizing liquid is composed of China wood oil and 
a hard resin like copal, the resulting calcium resinate 
becomes insoluble in oil, so that oil dripping on a 
floor of this kind does not disintegrate the Portland 
cement. Oil collecting on an unpainted concrete floor 
will cause the floor to become as soft as cheese in time, 
and then there is no remedy for it excepting to take up the 
floor and put down a new one. There is no record that 
China wood oil and copal had ever been used on Portland 


154 CHEMISTRY AND TECHNOLOGY OF PAINTS 


cement floors prior to the application in question, and 
that this patent was new and useful is demonstrated by 
the fact that there are practically at this writing over 
forty Portland cement paints on the market, all of them 
based on the same theory. 

In 1910 it was suggested that zinc sulphate be used to 
overcome the pernicious action of the free lime in Port- 
land cement, and for a time this material had quite a 
vogue, but it has turned out that no man could tell how 
much zinc sulphate to use, for no man knew definitely the 
amount of free lime in any 
large area of Portland ce- 
ment, and therefore either 
too much or too little was 
used. If too little was used 
there was still some free 
lime left; if too much was 
used sulphate of zinc crys- 
tallized out, and when the 
wall or floor became wet, 
either through rain or 
through washing, the film 





No. go. Highly magnified view of a 
fine crack in Portland cement con- of paint peeled off. 


struction —an example of incipient Practically all the paints 


disintegration. 
for Portland cement that — 


are on the market contain either China wood oil or a 
copal resin or both. Those composed of both of these 
materials have given the best satisfaction. Where ten 
years ago there was only one of these paints on the 
market today there are a large number, and it 1s 
estimated that more than a million gallons per year 
at this writing are used for the surface protection of 
Portland cement. 


MIXED PAINTS Iss 


PAINT CONTAINING PORTLAND CEMENT 


There is only one paint in existence thus far that 
contains a material equal to Portland cement, which 
is a tricalcium silicate and dicalcium aluminate, and 
which on setting liberates lime. This paint is known as 
“Tockolith,” and it has been and still is very largely 
used among engineers for the protection of steel against 
corrosion. 

The author cannot go into this subject any more 
deeply because this discovery is his and he is interested 
in the manufacture of this material, and furthermore, 
this book is not the place to exploit a proprietary article; 
but inasmuch as this paint has been regarded by many 
engineers as at least a step toward the solution of the 
question of the protection of iron and steel, it is fitting 
that this brief mention of the material should be made. 


DAMP-RESISTING PAINTS 


Paints of this character are comparatively new, the 
first one having been manufactured by the author’s firm 
and put on the market in 1892. It was made for the 
purpose of coating brine pipes and pieces of machinery 
which were continually under water. ‘The original paints 
of this character were produced by melting a good grade 
of asphaltum and adding a sufficient quantity of gutta- 
percha together with a suitable solvent and a small per- 
centage of pigment. These paints served their purpose 
very well and were used very largely, but no matter how 
carefully compounded the gutta-percha separated from 
the asphalt base if the paints were allowed to stand for 
any length of time. 


156 CHEMISTRY AND TECHNOLOGY OF PAINTS 


Further experiments showed that cement mortar 
would adhere most firmly to such a paint. The paint 
could be applied even to a new brick wall, lathing 
and furring being omitted. It took such a long time, 
however, to introduce a paint of this character to the 
building public that the author’s firm never thought it 
worth while to patent the application. 

Damp-resisting waterproof paints are now an adopted 
fixture in the paint industry, and while bitumen forms 
the base of paints of this character, treated China wood 
oil, and treated linseed oil in which glycerine is replaced 
with a suitable metallic base, should be added when 
making these paints. They are used widely and in 
various ways, having served their purpose so well that 
engineers are beginning to adopt such paints as priming 
coats for metallic structures wherever cement or cement 
mortar is to be applied, so that oxidation by electrolytic 
action may be prevented. 


ENAMEL PAINTS 


Enamel paints in former years were pigments ground 
in varnish, which dried with a high gloss. Some people 
objected to this high gloss, and where a good grade of 
varnish was used the film was rubbed with pumice stone 
and water until it produced an egg-shell finish. This 
then led to semi-gloss enamel paints, and finally we have 
the misnomer of having perfectly flat enamel paints 
today, for the very word ‘‘enamel”’ indicates gloss. 

For decorative use the principal enamel paints are 
white, but it must be said at the outset of the chapter 
that this subject cannot be thoroughly treated in this 
book. It has become so vast that it would take a book 
of this size alone to do the subject justice. There are 


MIXED PAINTS 157 


vast quantities of enamel paints made which are colored, 
but these are principally used for machinery of all kinds, 
for automobiles and for the so-called enamelling of various 
utensils, such as tool handles and the like. There are 
also vast quantities of black enamels made for technical 
purposes, and these are used for the manufacture of oil- 
cloth, patent leather and mechanical appliances. Those 
for oilcloth and patent leather are true oil enamels; 
those for mechanical appliances are principally made on 
an asphalt base. This chapter will treat of the subject 
of enamel paints for decorative purposes, which are 
principally white and mainly based on zinc oxid ground 
in a varnish or varnish oil. 

Prior to the mixed paint era white enamel was made 
by taking zinc oxid ground in either poppy oil or a 
bleached linseed oil, and thinning it with damar varnish 
as it was needed, and the painter did this himself. But 
as ready for use enamels were demanded improve- 
ments were made on this type of material. Today 
the three types of white enamels are: 

First. The zinc oxid types ground in damar varnish. 

Second. The lithopone types ground in China wood 
oil and rosin varnishes. 

Third. The zinc oxid types ground in stand oil only.! 

The damar type first mentioned is simple to make, but 
produces an enamel which does not flow out, which sets 
very quickly and which sometimes settles hard in the 
package and sometimes does not, depending entirely upon 
the gum damar used for the purpose. There are a great 
many varieties of gum damar whose acid figure ranges 
from 8. to 26., but the acid of gum damar is very weak | 
as compared to the acid of the majority of copals, and 


1 Stand oil has been described on page 184 in the chapter on 
Linseed Oil. 


158 CHEMISTRY AND TECHNOLOGY OF PAINTS: 


does not readily unite with a base Jike zinc; therefore 
a damar type enamel remains in suspension for several 
years. For enamel purposes damar varnish is usually cut 
cold, that is to say, six pounds are dissolved in a gallon 
of solvent in an ordinary vessel at room temperature; 
the resulting varnish is always cloudy, due to occluded 
water in the damar. To remove the latter the cold-cut 
damar is placed in a steam-jacketed kettle and heated to 
about 220° with steam under pressure. Steam at atmos- 
pheric pressure has a temperature of 212° F., so that at 
least ten pounds pressure is necessary in a steam-jacketed 
kettle to drive off the moisture contained in damar; but 
when this is done the damar darkens unless the operation 
is carried out in an aluminum or silver-plated kettle. 
Such solvents like cymene, toluol and xylol are added 
up to 5 per cent to damar varnish to overcome the 
cloudiness with fairly good results, but the action is not 
immediate, and the damar must be tanked for a con- 
siderable time. 

The second type, or lithopone and China wood oil- 
rosin varnishes, are very good for household use, but not 
so good for painting furniture, unless the varnish is 
made by an expert varnish maker with a minimum amount 
of rosin and the maximum amount of China wood oil, 
otherwise varnish of this type becomes hygroscopic in 
damp weather or sticky in hot weather. White pigments 
other than lithopone are not recommended for enamels 
of this type because of the high acid figure of the varnish. 

The third type, in which stand oil or linseed oil and 
zinc oxid are used alone, is the popular type of today, 
but has the disadvantage of drying slowly, yet this type 
of enamel will last for many years, and stands exposure 
even in the American climate for about eighteen months. 
It is made as follows: 


MIXED PAINTS 150 


Ten pounds of zinc oxid are ground in ordinary raw 
linseed oil, and this paste after having been finely ground 
two or three times is mixed with one gallon of stand oil, 
and then a gallon or less of turpentine or a mixture of 
turpentine and turpentine substitute is added. When 
made in this manner it takes 110° F. of heat four or five 
hours to dry it so that it is free from tack. 

Another method is to grind ten pounds of zinc oxid in 
japan drier, which may be a drier made of resinate of 
manganese and lead, and then add ten pounds of this 
paste to one gallon of stand oil. This will air-dry in five 
hours, and while it gives good results for interior pur- 
poses it is not recommended for exterior use. 

A third method of making these enamels is to grind 
the zinc oxid together with the stand oil in a roller mill, 
and then reduce with the necessary quantity of diluent 
and drier and strain very carefully. 

All enamels made along these lines have a tendency 
to turn yellow in the dark. Some, in fact, turn exceed- 
ingly yellow —almost the color of beeswax — depending 
upon the amount of chlorophyll or green coloring matter 
in the original linseed oil, and no method has yet been 
devised whereby this can be prevented. Many experi- 
ments have been made by the author tending toward 
improving this with partially good results, such as, for 
instance, the addition of an oxidizing material like 
hypochlorite of lime to the enamel. 

From the foregoing it is clearly evident that enamel 
paints may be nothing more or less than pigments ground 
in boiled linseed oil without the addition of any resin or 
gum, and the effect produced is that of high gloss and 
flexibility. 


160 CHEMISTRY AND TECHNOLOGY OF PAINTS 


FLAT WALL PAINTS 


Flat wall paints have come into existence in the 
United States, and it is estimated that hundreds of thou- 
sands of gallons are now made yearly, and that they 
give excellent results. Most flat wall paints contain 
lithopone as a pigment, the photogenic quality of which 
does not play a great réle in interior painting. Many 
of the flat wall paints contain as high as 20 per cent of 
water in the form of an emulsion, as is the case where the 
water is admissible in mixed paints; for in England the 
flat wall paints which are sold under a different name, 
either in paste form or ready for use, are all white paints 
containing a small percentage of linseed oil, and are the 
reverse practically of the American type of paints. They 
are called washable in England when they are washed 
from the bottom up, for when they are washed from the 
top down and the water streaks the wall there is danger 
of dissolving some of the paint and producing a bad effect; 
whereas the American types of wall paints, even those 
that contain 20 per cent of water, withstand the action 
of washing either from the top down or from the bottom 
up. There are, of course, many types which contain 
no water, the principal vehicle for this type of paint 
being a semi-fossil damar mixed with linseed oil or more 
generally a rosin-China wood oil varnish containing over 
50 per cent of solvent. 

Many of the failures of the flat wall paints which 
peel and disintegrate are due to the sizing on which they 
are painted. Glue, shellac or cheap varnish sizings are 
generally worthless on plastered walls, while an oily resin 
acid type of filler gives results which are permanent. 


MIXED PAINTS 161 


FLoor PAINTS 


Wooden floors are painted as a rule with a varnish 
paint which dries hard over night and produces a wear- 
resisting waterproof surface. In composition, paints for 
wooden floors are analogous to paints for concrete floors, 
-and are composed of a minimum amount of oil which 
dries by oxidation and a maximum amount of hard resin 
varnish. ‘The rosin varnishes, particularly those of the 
China wood oil type, do not wear as well as the hard 
resin varnishes. 

The pigments used in floor paints do not play a great 
role. Numerous experiments made show, for instance, 
that zinc oxid is not a useful pigment for the reason that 
the acid number of a floor paint varnish is sufficiently 
high to combine with the zinc and form an unstable paint 
—one which thickens up in the container and becomes 
unfit for use in a few months. Therefore lithopone is 
found very useful, and the inert pigments are preferred 
also for this reason. 


SHINGLE STAIN AND SHINGLE PAINT 


Shingle stain is not to be confounded with shingle 
paint. A stain for shingles is translucent; a paint for 
shingles is opaque, and the difference between the two 
is quite marked. One shows the grain of the wood, and 
the other gives a painted effect and does not show the 
grain. There is hardly any difference between shingle 
paint and the average ordinary mixed paint, with the 
exception that some manufacturers add asbestine in 
order to give it some fire-resisting quality. On this point 
it is well to mention that shingles that are painted, par- 
ticularly with a paint that has a fire-resisting quality, 


162 CHEMISTRY AND TECHNOLOGY OF PAINTS 


are superior to those coated with shingle stain, even 
though they may not look as artistic, because sparks 
flying from a chimney on a roof that has been stained 
and has thoroughly dried out are very likely to ignite 
the roof. 

Shingle stain is generally made from the very brilliant 
pigments and crude creosote. These pigments are as a 
rule ground in linseed oil, and two pounds are generally 
added to a gallon of creosote. Ordinary creosote oil is 
used for this purpose, probably because it has some wood 
preservative quality. Other manufacturers use ordinary 
kerosene and take two pounds of the strongest colors in 
oil that they can get. Still other manufacturers use 
crude carbolic acid or crude cresol and kerosene, but 
in spite of all these treatments shingles rot just the same. 
It is the soft pastel effect which a shingle stain gives that 
commends it so highly; but the same pastel effect is 
produced with shingle paint after the lapse of a year 
or two,. provided a good paint is properly reduced with 
about 50 per cent of volatile solvent. 

On new work shingles are generally dipped. A bundle 
is taken and dipped into a barrel and allowed to soak 
so that the wood will absorb all that it can. On old 
work, of course, it must be applied with a brush. 

Asbestine is frequently added in the proportion of 
one pound to the gallon of shingle stain containing heavy 
colors to prevent them from settling. One of the most 
difficult shingle stains or shingle paints to produce is a 
permanent red. For this purpose the oxids of iron 
(Fe.O;) are used, but wherever oxid of iron is exposed to 
the sunlight in the presence of linseed oil or other organic 
oils it probably changes to a ferroso-ferric condition, 
becomes considerably darker and is converted into a 
brown. This is less noticeable in a shingle stain than it 


MIXED PAINTS 163 


is in a shingle paint, because the shingle stain is largely 
composed of a volatile solvent, and the small amount of 
binder has relatively a lesser action than the binder in 
the shingle paint. It has been suggested, and there is 
probably some value to the suggestion, that potassium 
ichnomate to the extent of one ounce to the gallon 
should be ground in crystalline form with the paint 
in order to prevent any reduction. Hypochlorite of 
lime has also been suggested, and of the two the 
hypochlorite would be the better as long as it would last, 
because it would not wash out and be likely to stain the 
building. Dichromate would be very likely if it ran over 
the gutters or leaders to produce a bad stain. 


CHAPTER XII 


LINSEED OIL 


Tuts oil is still the principal oil used in the manu- 
facture of paints, and within the last ten years very 
extensive work has been done on the constants and 
specifications for linseed oils generally, as will be noted 
from the reports of the American Society for Testing 
Materials and several other reports quoted by the author. 

The raw linseed oil produced in the United States 
comes principally from the northwest. The foreign oils 
come from Calcutta, the Baltic, and the Argentine 
regions. There is considerable difference between these 
oils, the Baltic being perhaps the best and very highly 
prized by varnish makers. 

The constants of linseed oil show very wide variations; 
for instance, its specific gravity will run from 0.931 to 
0.935. Its iodine value will vary from 160 to 195 or 
more, while the saponification value will run between 
190 and 196. The greatest differences are found in 
North American linseed oil, the figures being sometimes 
so perplexing that it is difficult to reconcile them with 
the standards of Baltic oil. These discrepancies are 
easily traceable to the natural impurities found in Ameri- 
can linseed oil, as, for instance, oils from weeds growing 
in the flax fields. American linseed oil is likewise 
inclined to show the presence of water to a greater 
extent than fore gn oils, but this, however, is a question 
of age. If raw linseed oil is allowed to settle until it 


becomes perfectly clear and shows no sediment or tur- 
164 


LINSEED OIL 165 


bidity at o° C., it cannot be said to contain water. 
The question here naturally arises as to the use of the 
term “pure.” Calcutta and the Baltic seed are freer 
from foreign seeds than the American product, and 
although the amount of foreign seeds which appear as 
weeds in the field is very small, their presence alters the 
chemical and physical characteristics of the American 
oil. Taking Baltic as a standard, it could be reasonably 
argued that American linseed oil is adulterated, yet no 
man would have a moral or legal right to condemn 
American linseed oil because it differed from the Baltic. 
On the other hand both climate and soil have a well- 
known influence on vegetation; even the percentage 
of oil derived from a given seed cannot be said to be 
constant. It is also stated that virgin soil produces 
better seed than a replanted field and this statement 
appears reasonable. 

To how great an extent the natural or negligible 
admixture of the oil from foreign seeds to linseed oil 
affects the wearing quality of the oil, it is impossible to 
say, but it must be admitted that an oil containing up 
to 3 or 4 per cent of the oil of foreign seeds or weeds 
will not act as well in the kettle for varnish or boiling 
purposes as a purer oil. Taking these facts into con- 
sideration, a chemist must beware of giving an opinion 
as to the quality of linseed oil, and where there is no 
evidence either chemical or otherwise that the oil has 
been intentionally diluted with other materials no 
adverse opinion should be forthcoming. If the exam- 
ination of linseed oil shows an appreciable percentage 
of paraffin oil, it can. be positively inferred that no 
weed growth had anything to do with this adulterant 
and the mixture must be regarded as intentional or 
accidental. 


166 CHEMISTRY AND TECHNOLOGY OF PAINTS 


Raw linseed oil is extracted from the seed by the 
old-fashioned method of grinding the seed, heating it, 
placing it between plates and then pressing it until the 
remaining cake contains the least possible quantity of 
oil. The newer method is a continuous process by which 
the seed is ground and forced in screw fashion through a 
tube, the oil oozing slowly through an opening in the 
bottom of the tube and the cake falling out at the end 
in flakes. When the seed is fed in this manner without 
heating, a better quality of oil results. The third 
method consists in crushing the seed and extracting the 
oil by means of naphtha. The resulting liquid is evapo- 
rated, the naphtha recovered and the oil sold for painting 
purposes. It appeared, however, that this process, while 
very profitable for the manufacturer, was not profit- 
able for the consumer, and although it made a very 
fair paint oil, it was found that for the purpose of coating 
leather, oilcloth, and window shades, the oil had the 
unfortunate faculty of soaking through the fabric, and 
when a piece of goods was rolled up too soon and 
allowed to stand for the greater part of the year it 
was almost impossible at the end of that time to unroll 
the goods, the whole having become a solid mass. Inves- 
tigation showed that some of the proteids in soluble 
form were extracted by the naphtha. This was called 
“new process oil,” and it was generally understood that 
cake made from new process oil was not as good cattle 
feed as cake made in the old-fashioned way, probably on 
account of the removal of part of the proteids. 

If linseed oil were uniform, both as to source and 
nature of seed, a chemical formula could be established 
for it, but because it is not uniform the acids cannot 
be given in quantitative relation. Linseed oil should 
give no test for nitrogen; if it does, the proteids in the 


LINSEED OIL 167 


seeds have been attacked. Probably 95 per cent of all 
the linseed oil made is sold in the raw state, and, strange 
to say, probably 95 per cent or over of all the linseed 
oil used is consumed in any other but the raw state. It 
must not be inferred that all paint manufacturers 
manipulate or treat their linseed oil by heat and other 
methods of oxidation, for, whilesmany of them claim to 
do so, not one that the author is acquainted with could 
afford to handle and manipulate linseed oil. At the same 
time, raw linseed oil cannot be used for the purpose of 
making paints unless a drier be added, and from the 
very moment that the drier, either in the nature of a 
siccative oil, resin, or Japan, is mixed with the oil, the 
chemical constants of the oil are altered. The change is 
an irreversible reaction. As an example, it may be cited 
that if 90 per cent of linseed oil be mixed with to per 
cent of volatile constituents and Japan driers, the chemist 
cannot separate the three substances and produce three 
vials containing raw linseed oil in the state in which it was 
used, and the drier in an unaltered condition. The volatile 
solvent, if it be benzine, is the only one of the three that 
can be recovered in any approach to its original condition. 

The literature on- raw linseed. oil is very incomplete, 
and more attention should be paid by chemical experts 
and writers to the subject of identification of linseed 
oil as it really exists in the paint. 

In the chapter on the “Analysis of Oils” it will be 
seen that when the iodine number of an oil is 180 the 
same oil when extracted from mixed paint may show IIo 
and still be absolutely pure, for the reason that the 
metallic salts which have been added to the oil in the 
form of Japan or other siccatives have in a measure 
saturated some of the bonds of the linseed oil, so that 
less iodine or bromine is absorbed. 


168 CHEMISTRY AND TECHNOLOGY OF PAINTS 


Linseed oil dries by oxidation, and this oxidation is 
hastened by the addition of bases or salts of lead and 
manganese. There is no doubt that some of these act 
catalytically, and there is likewise no question that some 
of these driers continue to act long after the oil is phys- 
ically dry. In drying, raw linseed oil is supposed to 
absorb as much as 18 per cent of oxygen, but in actual 
practice where solid linseed oil is used as an article of 
commerce it seldom absorbs more than to per cent of 
its original weight. The addition of a drier has much to 
do with the life of a paint, there being no two driers 
that act exactly alike. If it is the intention of the paint 
manufacturer to make a paint that will last the longest, 
he must study the chemical and physical characteristics 
of the drier which he uses. Red lead (Pb;O,;) added to 
linseed oil at a temperature up to 500° F., will make a 
very hard drying film which in time becomes exceedingly 
brittle. This can be very easily demonstrated if the red 
lead oil be coated on cloth and its effect closely watched. 
On the other hand, the addition of litharge to linseed oil 
produces the opposite effect, and an exceedingly elastic 
film is produced. The various manganese salts all act 
differently and are frequently used to excess. Manganese 
starts the drying operation, the lead salts continue it, and 
the manganese again hastens the end. Borate of man- 
ganese is, perhaps, the least objectionable of all man- 
ganese salts, but the black oxid or peroxid is most 
largely used, and if not used in excess is an exceedingly 
valuable assistant in the drying of linseed oil. 

These driers are usually prepared by adding the oxids 
of lead and manganese to melted rosin. After a resinate 
of lead and manganese is produced, a small quantity of 
linseed oil is added and the mixture then cooled either 
with turpentine or benzine or both. There are hundreds 


LINSEED OIL 169 


of varieties of the so-called Japan driers, the best ones 
containing the minimum amount of rosin and a certain 
percentage of the dust of Kauri gum. The oil driers 
are made in a similar way, excepting that no rosin is 
used, and these driers do the least harm. Lime is very 
frequently used in addition to oil, sometimes in con- 
junction with rosin and sometimes alone, in order to 
produce a drying effect. The so-called lime oil will dry 
with a hard and brittle film. The salts of lead and man- 
ganese are not as good for mixed paint purposes as they 
are for technical purposes. The chloride of manganese 
when added to linseed oil reacts upon it, and in the 
presence of any moisture in the oil will liberate traces of 
hydrochloric acid. Sulphate of manganese and lead 
acetate will act similarly, and wherever there is a trace of 
liberated acid in paints their rapid and uniform drying 
is interfered with. Zinc sulphate and lead sulphate are 
also excellent driers. It is considered good practice to add 
a small amount of calcium carbonate wherever these 
driers are used in order to neutralize the acidity, and 
when this is done no ill effect can be observed. Prob- 
ably the most flexible drier is Prussian blue, which is 
soluble in linseed oil at 500° F., and produces such a 
flexible film that the patent leather industry is based 
upon it. 

Some twenty-three years ago the author manufactured 
a new drier which is an improvement on Prussian blue. 
Briefly described, this drier is made out of a by-product 
Prussian blue which is treated with an alkali in the 
presence of calcium oxid and water. A brown powder is 
the result, which has no uniformity of color but has 
given excellent results as a drier. This brown has been 
erroneously called ‘“‘Japanners Prussian Brown,” or 
Japanese brown. It is soluble in linseed oil at 500° F., 


170 CHEMISTRY AND TECHNOLOGY OF PAINTS 


and produces a film which is neither too hard nor too 
soft, but remarkably elastic and admirably adapted for 
making certain paints and varnishes. It cannot, how- 
ever, be said to replace any of the good linseed oil driers 
for mixed paints, where too flexible a paint is not desir- 
able, particularly on steel work or exterior work, as 
blisters are likely to result from the difference in expan- 
sion. However, as a base for the manufacture of enamel 
varnishes and oils this drier has proved itself admirably 
adapted. 

Linseed oil is a glyceride of several fatty acids, and 
Lewkowitsch has proved that water will replace the 
glyceride radical and hydrolize the oil. (See “New Paint 
Conditions Existing in the New York Subway” by 
Maximilian Toch, Journal of the Society of Chemical 
Industry, No. 10, Vol. XXIV.) 

The action between a fat and a caustic alkali in boil- 
ing solution, by which a soap is formed and glycerin set 
free, is too well known to need further discussion. The 
fatty acids which are combined with the soda can be 
liberated by the addition of almost any mineral acid to 
the soap. This saponification can be produced by the 
action of water alone on raw linseed oil. Where a paint 
contains lime or lead this hydrolysis probably is hastened. 

We have here an excellent explanation of the so- 
called porous qualities, or non-waterproof qualities, of 
linseed oil as a paint, which is further brought out by 
the fact that when linseed oil is treated with Prussian 
blue or Japanners brown it cannot be hydrolized by 
means of water, for the acid radicle has formed a com- 
plete compound with the iron in both of these driers, and 
the prolonged heating has volatilized the glycerin. Con- 
sequently, when a paint is made by the treatment of 
linseed oil at a temperature of over 500° F., with a 


LINSEED OIL Lat. 


neutral and soluble base like the ferri-ferro cyanide of iron, 
the resulting film is not linseed oil nor a linoleate of any 
base with free glycerin, but a complex compound com- 
posed of the various linseed oil acids united with iron. 
This gives us the basis of waterproof paints. This is 
evident from the quality of patent leather, which is not 
only much more flexible than any paint made in the 
ordinary way, but is likewise waterproof. Waterproof 
paints are, however, made at the present time by eliminating 
linseed oil and substituting China wood oil and perilla oil. 
_ There are questions in regard to the physical and 
chemical characteristics of linseed oil on which there has 
been considerable discussion and naturally a difference 
of opinion. The first is whether linseed oil dries in a 
porous film, and the second is whether linseed oil while 
drying goes through a breathing process during which 
it absorbs oxygen and gives off carbonic acid and water. 
With reference to the porosity of the dry film of linseed 
oil, the following extract is made from the Journal of 
the Society of Chemical Industry (May 31, 1905, ‘“‘New 
Paint Conditions Existing in the New York Subway” 
by Maximilian Toch). 


72 CHEMISTRY AND TECHNOLOGY OF PAINTS 


“In a paper before the American Chemical Society 
on March 20, 1903, I gave it as my opinion that a dried 
film of linseed oil is not porous, excepting for the air 
bubbles which may be bedded in it, but that any dried 
film of linseed oil subjected to moisture forms with it a 
semi-solid solution, and the moisture is carried through 
the oil to the surface of the metal. We then have 
two materials which beyond a doubt have sufficient 
inherent defects to produce oxidation under the proper 
conditions, and granted that the percentage of carbon 
dioxid in the air of the tunnel is not beyond the normal, 
the fact that carbon dioxid together with moisture would 
cause this progressive oxidation is sufficient warrant for 
the discontinuance of paints that are not moisture and 
gas proof. Dr. Lewkowitsch demonstrated in his Canton 
lectures that the fats and fatty oils hydrolized with 
water alone, and linseed oil is hydrolized to a remarkable 
degree in eight hours when subjected to steam. It can, 
therefore, be inferred that water will act on linseed oil 
without the presence of an alkali, and that calcium added 
to water simply hastens the hydrolysis by acting as a 
catalyser. This, then, bears out my previous assertion 
that a film of linseed oil (linoxyn) and water combine to 
form a semi-solid solution similar in every respect to 
soap, and inasmuch as we have lime, lead, iron and 
similar bases present in many paints, it is almost beyond 
question that these materials aid in the saponification 
of oil and water.” 

If a drop of linseed oil is spread on a glass slide and 
one half of it covered with a cover glass, it will be readily 
seen under the microscope that the dried film is as solid 
as the glass itself, that there are no pores nor any 
semblance to a reticulated structure visible in the oil, 
and the author therefore makes the statement with 


o> 





No. gt. D is a glass flask of about 2 litres capacity. Through the tube A 3.4 grams of refined 
linseed oil, which had been heated to 400 degrees F. for one hour, were introduced and well 
distributed over the inner surface of the flask. Dry oxygen free from COz2 was blown through 
the flask, by means of tubes A and C, until the flask contained pure oxygen. ‘The tube A was 
then sealed, as shown in sketch, mercury brought up into the manometer by elevating B to the 
position shown. The flask was then filled with oxygen at atmospheric pressure and effectually 
sealed. As drying proceeded and oxygen was absorbed, the diminished pressure was read off 
on the manometer. When this became constant the funnel which was connected to A by a rubber 
tube was filled with filtered Barium Hydrate solution, and the point at A broken, allowing this 
to run into the flask without admission of air. In a few minutes Barium Carbonate was formed, 
showing conclusively that some COz had been generated by the oil. 


173 


174 CHEMISTRY AND TECHNOLOGY OF PAINTS 


absolute certainty that linseed oil dries with a homo- 
geneous film in all respects similar to a sheet of gelatin 
or glue. 

The question as to whether linseed oil goes through a 
breathing process, absorbing oxygen and liberating car- 
bon dioxid and water, is one of great importance and 
one which the author has worked out very carefully with 
positive results. In the illustration a piece of filter paper 
two inches in diameter was dipped in linseed oil of known 
purity and suspended in a flask in air absolutely free 
from CO, and water. Investigators have always com- 
plained of the inability to obtain tight joints in an 
experiment of this kind, and in order to be certain that 
there was no leakage all joints were covered with 
mercury after having been first shellacked. The mano- 
meter gave a curve which indicated the drying, a 
thermostat being a part of this instrument, so that 
absolutely uniform conditions were obtained. At the 
end of thirty days the drying curve was obtained, and 
when the baryta water was led into the bottom of the 
flask there was hardly a trace of turbidity to be noted. 
This experiment was repeated many times, always with 
the same result, and the amount of water or moisture 
obtained could not be weighed. It was therefore reason- 
able to conclude that the linseed oil gave off neither CO, 
nor water, but had absorbed oxygen. 

The author, however, concluded that this experiment 
was entirely too delicate, inasmuch as only one gram of 
linseed oil was absorbed by the paper. Therefore, an 
apparatus was devised as shown in the illustration, 
without joints and so absolutely air-tight that the ques- 
tion of leakage could not arise. The flask was filled with 
linseed oil and then emptied by replacing the oil by air 
free from water and CO,, the inside and bottom of the 


LINSEED OIL 175 


flask being left heavily coated with linseed oil which had 
been previously heated to 4oo° F., for one hour. The 
manometer tube formed a part of this apparatus, and 
when the oil had dried completely (which was manifest 
by its wrinkled and bleached appearance and likewise 
by the manometer indication) a rubber tube was attached 
to the point E, a funnel inserted, and a filtered solution 
‘of barium hydrate was allowed to run in as soon as the 
tip E was broken. After ninety seconds the solution of 
barium hydrate turned milky, showing conclusively that 
CO, had been generated in the drying of linseed oil. 

The next experiments were made quantitatively, and 
while the amount of moisture could not be accurately 
measured, the amount of carbon dioxid was in no case 
higher than ;) of rt per cent, whereas the absorption 
of oxygen was 19g percent. It must therefore be admitted 
that linseed oil does give off CO., but the quantity is 
relatively so small that it is a question whether it should 
be taken into account at all. 

It is now a known fact that carbon dioxid acts as a 
rust-producer on iron or steel, and if linseed oil gave off 
any appreciable quantities of CO, and water they would 
act as rust-producers in themselves rather than pro- 
tectors; and while it may be possible that some linseed 
oils give off more of these two substances than others, 
the amount under normal conditions cannot be very 
great, as these experiments show. 

Refined or bleached linseed oil is used to a very great 
extent for the manufacture of white paints. The methods 
employed for bleaching linseed oil have not undergone 
very much change until lately. The coloring matter in 
linseed oil is largely chlorophyll, the bleaching of linseed 
oil depending not on the extraction of this chlorophyll 
but on its change into xantophyll, which is yellow. 











b 
| 





No. 92. DETERMINATION OF CO, AND H2O IN DryING oF LINSEED O11 —A 
piece of filter paper was immersed in pure linseed oil, and, after the absorbed 
oil was weighed, the filter paper was suspended in the Erlenmeyer flask, on 
the bottom of which was a solution of Barium Hydrate (free from COz2) to absorb 
the CO, formed by the drying of the oil. The flask was immersed in a water- 
thermostat, the water of which was stirred by a revolving mechanical stirrer. 
A thermo-regulator, by means of which the gas-flame under the thermostat was 
automatically regulated, was placed under the flask. By opening the glass- 
cock, oxygen was admitted from time to time to the Erlenmeyer flask, and the 
absorption of oxygen was read on the mercury-manometer. ‘The readings were 
always made at the same temperature. The oxygen, before entering the Erlen- 
meyer flask, was passed through the KOH bulb, where it was washed free from 
CO:. This experiment was conducted in triplicate with great care, the joints 
being all sealed with shellac and placed under mercury. No CO: or H2:O beyond 
a trace could be determined, owing to the small quantity of linseed oil which the 
filter paper contained. 





176 


LINSEED OIL 177 


Sometimes linseed oil will have a reddish cast instead 
of the usual greenish cast. This color is attributed to 
another form of organic matter known as erythrophyll. 
These three tints, the green, yellow, and red, are analogous 
to the tints in autumn leaves. 

All methods for extracting chlorophyll from linseed oil 
have proved extremely difficult and expensive. The ac- 
cepted method, therefore, has consisted in the treatment of 
linseed oil with an acid in order to convert the green coloring 
matter into the yellow. This is probably the reason why 
no linseed oil exists which is water white, although the 
author has made several samples which are almost color- 
less, but when compared in a four-ounce vial with chemi- 
cally pure glycerin it can readily be noted how far from 
colorless the so-called bleached linseed oil is. The method 
employed for bleaching linseed oil consists in the addition 
of sulphuric acid and the blowing of air into the oil at 
the same time. The oil becomes cloudy and develops 
small black clots. When this cloudiness is allowed to 
settle out, or the oil is filtered through a filter press, it 
is very much paler in color, and is then known as refined 
or bleached linseed oil. 

Sunlight has a similar effect, the oil produced by 
bleaching with light and age being superior in quality 
to the sulphuric acid oil. In the sulphuric acid treat- 
ment the oil, the water, and “foots,” together with an 
appreciable amount of emulsified oil, settle to the bottom 
of the tank. These are drawn off, and are of some value 
for making cheap barn paints by mixing with lime and 
the oxids of iron. In another method, which produces a 
still better bleached oil, chromic acid is used. If a 
solution of this acid, which is blood red, be added to 
linseed oil, and the mixture agitated, a very much paler 
and more brilliant oil is obtained, but it is rather 


178 CHEMISTRY AND TECHNOLOGY OF PAINTS 


expensive to produce. The treatment by means of an 
electric current in the presence of moisture is likewise 
used to some extent, but it appears that this method is 
far more suited to other oils. Great secrecy is main- 
tained among those who have a knowledge on this 
subject. Peroxid of hydrogen has likewise been recom- 
mended, but from the standpoint of cost the sulphuric 
acid method is still the one that is used to the greatest 
extent. ; 

The new methods which are favorably spoken of, and 
which the author has found to be inexpensive and 
efficient, involve the use of the peroxids of calcium, 
magnesium, and zinc. These peroxids are made in‘o 
paste with water, one pound being sufficient for 200 
gallons of linseed oil. This amount of oil is placed in 
an open kettle or vat, together with the peroxid, and 
thoroughly agitated. During agitation a strong solution 
of sulphuric acid is added, which liberates nascent oxygen. 
If the oil be allowed to settle, or is filtered, and is then 
heated to drive off any traces of moisture, a very brilliant 
pale oil is obtained. 

It has always been understood that linseed oil con- 
tained albuminous matter which coagulated at a tem- 
perature of 400° F., or over, and produced a flocculent 
mass. When an oil answered this reaction it was said 
to “break”’ at the low temperature and was useless for 
making varnish oil and other high grades of linseed oil. 

G. W. Thompson found that this break was not due 
to the presence of albuminous and nitrogenous matter, 
but that it was caused by the separation of several 
phosphates. This explanation has generally been ac- 
cepted as correct. If an oil, therefore, is allowed to age, 
the phosphates settle out and the oil does not break. 
Cold-pressed linseed oil, if it breaks at all, does not break 


LINSEED OIL 170 


at as low a temperature as hot-pressed oil. Bleached 
linseed oil does not wear as well as the oil that has been 
clarified by standing. 

The demand for brilliant white paints or brilliant 
enamels is responsible for the manufacture of the so- 
called water-white oils. From a large variety of tests 
made by the author it was fully demonstrated that 
white paints composed of mixtures of pigments such 
as sublimed lead, zinc oxid, and white lead all showed 
absolutely the same whiteness within two weeks after 
they were exposed to the light, irrespective of the 
kind of raw linseed oil used. One of the five tests 
was made with a paint prepared with a linseed oil that 
had not been aged for more than two months, but 
within the time mentioned it was just as white as the 
rest. 

Linseed oil paints are supposed to deteriorate after 
a few years and lose their value, owing to the decomposi- 
tion of linseed oil. This statement is questionable, and 
while there is no doubt that the ready-mixed paint 
thickens and changes slightly in its chemical and physical 
characteristics, the change is exceedingly small in a con- 
tainer which is hermetically sealed. There is no doubt 
in regard to the reaction which takes place between the 
oil and white lead, zinc oxid, and a number of the 
unstable compounds in a mixed paint. While these 
reactions are very slow, they are at the same time very 
definite. If the value of a paint were reduced to a 
curve it would probably be found that the curve would 
be represented by the arc of a large circle approaching 
a straight line. As far as paste paints are concerned, 
particularly white lead, all painters prize white lead more 
highly when it is old than when it is fresh. 


180 CHEMISTRY AND TECHNOLOGY OF PAINTS 


Typical Analysis of Bleached, Refined Linseed Oil 


Specific, Gravity Sai.-Al ae rcs eon ene nae .932-.934 

Todine Values Hanus). 90.0. eee Above 180 

Saponifica tionsValuic iam (ec sey IQO-194 

AcidtY ale. ret eaeks cas yeast eee ee 355 
1924 


AMERICAN SOCIETY FOR TESTING MATERIALS 


STANDARD SPECIFICATIONS 
. FOR 
PuriITY OF Raw LINSEED OIL FROM NorRTH 
AMERICAN SEED 


Serial. Designation: D 1-15 


These specifications are issued under the fixed designation D 1; 
the final number indicates the year of original adoption as standard, 
or in the case of revision, the year of last revision. 


ADOPTED, 1913; REVISED, 1915 


I. PROPERTIES AND TESTS 


Ve Raw linseed oil from North American seed shall conform 


to the following requirements: 


Maximum Minimum 
(o) 


15-5 





Specific Gravity at ex Cee 0.936 GV 032 
I 
or 
: 25° 
Specific Gravity at He Cae 0,081 0.927 
2 
AcidsNumbérs nay eee eee 6.00 
Saponitication Number. see ss 195. 189. 
Unsaponifable matter, per cent... ere res 
Refractive:index-atay Gre ee I. 4805 1.4790 
Iodine Number (Hanus)......... ae 180 


IL. METHODS” OF TESTING, 


2. The recommended methods of testing are as follows: 
General. — All tests shall be made on oil which has been filtered 


LINSEED OIL 181 


at a temperature of between 60 and 80° F. through paper in the 
laboratory immediately before weighing out. The sample should 
be thoroughly agitated before the removal of a portion for filtration 
or analysis. 

Specific Gravity. — Use a pyknometer, accurately standardized 
and having a capacity of at least 25 c.c., or any other equally accurate 
method, making a test at 15.5° C., water being 1 at 15.5° C., ora 
test at 25° C., water being 1 at 25° C. 

Acid Number. — Expressed in milligrams of KOH per gram of 
oil. Follow the method described in Bulletin No. 107, revised 1908, 
Department of Agriculture, Bureau of Chemistry, page 142. 

Saponfication Number. — Expressed as with Acid Number. 
Blanks should also be run to cover effect of alkali in glass. Follow 
method given in Bulletin No. 107, revised 1908, Department of 
Agriculture, Bureau of Chemistry, pages 137-138. 

Unsaponifiable Matter. — Follow Boemer’s method taken from 
his Ubbelohde Handbuch Der Ole u. Fette, pages 261-262. ‘To 
too g. of oil in a 1000 to r500-c.c. Erlenmeyer flask add 60 c.c. of 
an aqueous solution of potassium hydroxide (200 g. KOH dissolved 
in water and made up to 300 c.c.) and 140 c.c. of g5-per cent alcohol. 
Connect with a reflux condenser and heat on the water bath, shaking 
at first until the liquid becomes clear. Then heat for one hour with 
occasional shaking. ‘Transfer while yet warm to a 2000-c.c. separatory 
funnel to which some water has been added, wash out the Erlenmeyer 
with water using in all 600 c.c. Cool, add 800 c.c. of ether and 
shake vigorously one minute. In a few minutes the ether solution 
separates perfectly clear. Draw off the soap and filter the ether (to 
remove last traces of soap) into a large Erlenmeyer and distill off the 
ether, adding if necessary one or two pieces of pumice stone. Shake 
the soap solution three times with 4oo c.c. of ether, which add to 
the first ether extract. To the residue left after distilling the ether 
add 3 c.c. of the above KOH solution, and 7 c.c. of the 95-per cent 
alcohol, and heat under reflux condenser for 10 minutes on the 
water bath. Transfer to a small separatory funnel, using 20 to 30 
c.c. of water, and after cooling shake out with two portions of 100 c.c. 
of ether; wash the ether three times with 10 c.c. of water. After 
drawing off the last of the water, filter the ethereal solution so as to 
remove the last drops of water, distill off the ether dry residue in 
water oven and weigh.” 


182 CHEMISTRY AND TECHNOLOGY OF PAINTS 


' Or, any accurate method involving the extraction of the dried 
soap may be used. 

Refractive Index. — Use a properly standardized Abbé Refrac- 
tometer at 25° C., or any other equally accurate instrument. 

Iodine Number (Hanus). — Follow the Hanus method as described 
in Bulletin No. 107, revised 1908, Department of Agriculture, Bureau 
of Chemistry, page 136. 


1924 
AMERICAN SOCIETY FOR TESTING MATERIALS 
STANDARD SPECIFICATIONS 
FOR 
Purity OF BorILED LINSEED OIL FROM 
NortH AMERICAN SEED 


Sertal Designation: D 11-15 


These specifications are issued under the fixed designation D 11; 
the final number indicates the year of original adoption as standard, 
or in the case of revision, the year of last revision. 


ADOPTED, IQI5 


I. “PROPERTIES AND THs Is 


t. Boiled linseed oil from North American seed shall conform 
to the following requirements: 


Maximum Minimum 





Specific Gravity at res CR sae 0.045 = 201g37 
Acid SN tim bei: oe eae ere 8. ESR aes 
Saponification Number.......... LOGE 189. 
Unsaponifiable Matter, per cent. .. 154 eee 
Refractive Index ate ceC es 1.484 1.479 
Iodine Number (Hanus) =.= 3) eee 178. 
ASH Der. Cent acer wae ee penne Oy On? 
Manganese, per ‘centia) 0.2 0.03 


Calcium, per-cent 
Lead, per gentax* 72 52 Map ay ee eee O.1 


LINSEED OIL 183 


TW. METHODS OF TESTING 


2. The recommended methods of testing are as follows: 
General. —The sample should be thoroughly agitated before 
_ the removal of a portion for analysis. 

Specific Gravity. — Use a pyknometer, accurately standardized 
and having a capacity of at least 25 c.c., or any other equally 
accurate method, making a test at 15.5° C., water being 1 at 
ras ouga On 

Acid Number. — Expressed in milligrams of KOH per gram of 
oil. Follow the method described in Bulletin No. 107, revised 1908, 
Department of Agriculture, Bureau of Chemistry, page 142. 

Saponification Number. — Expressed as with Acid Number. 
Blanks should also be run to cover effect of alkali in glass. Follow 
method given in Bulletin No. 107, revised 1908, Department of 
Agriculture, Bureau of Chemistry, pages 137-138. 

Unsaponifiable Matter. — Follow Boemer’s method taken from 
his Ubbelohde Handbuch Der Ole u. Fette, pages 261-262. “To 
100 g. of oil in a 1000 to 1500-c.c. Erlenmeyer flask add 60 c.c. of an 
aqueous solution of potassium hydroxide (200 g. KOH dissolved in 
water and made up to 300 c.c.) and 140 c.c. of 95-per cent alcohol. 
Connect with a reflux condenser and heat on the water bath, shaking 
at first until the liquid becomes clear. Then heat for one hour with 
occasional shaking. Transfer while yet warm to a 2000-c.c. separatory 
funnel to which some water has been added, wash out the Erlenmeyer 
with water using in all 600 c.c. Cool, add 800 c.c. of ether and shake 
vigorously one minute. In a few minutes the ether solution separates 
perfectly clear. Draw off the soap and filter the ether (to remove 
last traces of soap) into a large Erlenmeyer and distill off the ether 
adding if necessary one or two pieces of pumice stone. Shake the 
soap solution three times with 4oo c.c. of ether, which add to the 
first ether extract. To the residue left after distilling the ether add 
3 c.c. of the above KOH solution, and 7 c.c. of the 95-per-cent alcohol, 
and heat under reflux condenser for 10 minutes on the water bath. 
Transfer to a small separatory funnel, using 20 to 30 c.c. of water, 
and after cooling shake out with two portions of 100 c.c. of ether; 
wash the ether three times with 10 c.c. of water. After drawing 
off the last of the water, filter the ethereal solution so as to remove 
the last drops of water, distill off the ether, dry residue in water oven 
and weigh.” 


184 CHEMISTRY AND TECHNOLOGY OF PAINTS 


Or, any accurate method involving the extraction of the dried 
soap may be used. 

Refractive Index. — Use a properly standardized Abbé Refrac- 
tometer at 25° C., or any other equally accurate instrument. 

Todine Number (Hanus). — Follow the Hanus method as de- 
scribed in Bulletin No. 107, revised 1908, Department of Agriculture, 
Bureau of Chemistry, page 1306. 

Ash. — The determination of the percentage of ash and the 
constituents thereof may be made by any method which gives accu- 
rate results. 


STAND OIL 


Stand oil is a very heavy, viscous form of linseed oil 
which has great use in the arts for the manufacture of 
both air drying and baking enamels. It is supposed that 
it originated in Holland, but there is a difference of 
opinion on this for the reason that the table oilcloth 
manufacturers in Scotland made a similar oil under the 
name of “marble oil” long before the Dutch made any 
enamel paints. 

The method of making marble oil, which is a form 
of stand oil, is simply to heat a linseed oil which has 
no “break”! to 550° F., and to keep it at that tem- 
perature or slightly over until it becomes very heavy 
and viscous. Its specific gravity changes from .g30 to 
.g80, at which point a small quantity placed on a piece 
of glass and allowed to cool piles or stands up in a little 
mound and runs very slowly. With the oil still at 550° 
F., a small quantity of litharge is added; this is known 
as adding the drier on the downward cool, which simply 

1 An oil from which no black flocculent particles separate at 


500° F. is technically known as an oil which has no “break” or 
does not “break.” 


LINSEED OIL 185 


means that the oil takes up the drier not as the heat is 
increasing but as the heat is decreasing. The amount 
of litharge added is necessarily very small, because if 
more than one tenth of 1 per cent be added the oil 
becomes considerably darkened, while the object in 
making an enamel oil or marble oil is to retain its color. 
Oil made solely with litharge as a drier dries very tacky 
and must be baked to at least 110° F. for several hours 
before it will dry entirely. For this reason many add a 
small percentage of borate of manganese with the lith- 
arge, or chloride and sulphate of manganese, as a drier. 

Of all the driers for making stand oil for enamel 
paints cobalt is the best, for a very small quantity is 
necessary to perform the function of drying and no bad 
results are obtained. Where manganese driers are used 
and continued oxidation takes place a white enamel 
paint may turn entirely pink, due to the formation of a 
manganese salt of that color. Where lead is used slow 
and sticky drying may result, but where lead and 
manganese are used together in dark colored enamels 
excellent results are obtained and any change in color 
value is not noticed. 

Some stand oils are made also by partial oxidation or 
blowing and partial heating. ‘These, however, are short, 
and when placed between the thumb and forefinger and 
rubbed rapidly do not form a long thread but a short 
thread. Experience has taught that a short oil is short 
lived and a long oil is long lived. There is obviously a 
good reason for this, as the short oil has been highly 
oxidized and continues to oxidize after it is dry. Yet for 
interior enamel purposes a short enamel oil will last many 
years. 

One of the best features of enamel oil or stand oil is 
that brush marks even with a poor brush are eliminated 


186 CHEMISTRY AND TECHNOLOGY OF PAINTS 


and flow together. Zinc oxid is the principal pigment used 
in the manufacture of all of these enamel paints. 


JAPANNER’S BROWN OIL 


This is a stand oil or marble oil identical in all 
respects with that described under the heading “Stand 
Oil,” excepting that it is dark in color and therefore 
only used for making dark colored enamels such as 
patent leather, machinery enamels and waterproof coat- 
ings which must have a high glaze. 

The method used for making this oil depends very 
largely upon the good quality of the linseed oil, and the 
oil must have no tendency to “break”? whatever. It 
must be heated to 550°, at which temperature Japan- 
ner’s Brown is added slowly in the proportion of three 
ounces to the gallon until the oil, which at first is muddy, 
becomes clear and of the color and consistency of dark 
honey. 

As the present tendency is to varnish or enamel auto- 
mobile parts and bake them at fairly high temperatures 
this oil has become of great value, particularly when 
mixed with a fossil resin varnish, and as there are but 
very few automobiles which are painted white the dark 
color of this particular oil is no objection. 

For the manufacture of an enamel paint for painting 
engines which are continually at a temperature of be- 
tween 170° and 212° F. on account of being water jacketed, 
it has been found that the dark enamels used for this 
purpose when made with the Japanner’s Brown oil con- 
taining at least 25 per cent of a high grade fossil resin 
varnish give results that are astonishing. Enamel paints 
on an engine, composed of the materials just described, 
will at the end of a year be practically as good as the day 
that they were applied. 


LINSEED OIL 187 


MANUFACTURE OF STAND OIL AND BOILED OIL 


The tendency even at this writing is to manufacture 
both stand oil and boiled oil by rule of thumb. A certain 
kind of oil is put into a kettle, it is heated to a given 
temperature and drier added either before or after it 
thickens, and when the workman decides that the bead 
will pile, or that the string between the finger and the 
thumb is long enough, or that a cooled drop on glass is 
elastic, it is considered finished. This is not by any means 
the manner in which heavy bodied oils should be made, 
and there is no necessity for using rule of thumb methods. 

In the first place, the oil selected must be a non-break 
oil. In the second place, from previous experience it must 
be known how many hours to heat an oil slowly until it 
reaches the polymerization or thickening period. From 
time to time sufficient oil must be taken out and put in a 
cylinder, and the cylinder placed in cold water so that the 
temperature of testing is not over 70°. The specific gravity 
of the oil is taken, and if the standard sample of enamel 
oil should be .970, at which it will produce its best results, 
each subsequent batch should be heated until it has 
obtained that specific gravity. 

There are, of course, many methods by which these 
heavy bodied oils are made. Some are produced by means 
of boiling and blowing, and some by boiling alone, and 
some by blowing alone. ‘Those that are produced by 
the heat method which is popularly called boiling — but 
the oil never comes to a boil — give the best results because 
the acid number is lower and it does not continue to oxi- 
dize as quickly as blown oil always does. 

Where color counts only nascent cobalt drier should 
be used. Where color does not count, as for dark products, 
it is advisable to use mixtures of lead and manganese. 


188 CHEMISTRY AND TECHNOLOGY OF PAINTS 


Enamel oil must be kept light and many varnish makers 
use manganese borate as a drier. This alone is one of the 
poorest and most inefficient of driers, but when 4 of 1 per 
cent of cobalt soap is added to it there is hardly any per- 
ceptible difference in the color, and the oil will dry rapidly. 
A well made standardized stand oil will not liver or saponify 
with any pigment, and, when reduced with sufficient thin- 
ner, will flow out and obliterate brush marks. 

Some enamel makers add from 5 to to per cent (by 
weight) of No. 1 Singapore Damar. Where this is done 
it must be added to the oil while cooking, otherwise the 
resulting enamel will bloom. 


Typical Analysis of Heavy Bodied Blown Oil 


Specific:Gravity;.....- 62k er .988—.993 
Saponification, Vdlite. <a. ae 195-210 
Iodine Value rik 2 eee 100-140 
Acid Value: 5.0. 0228) Se We ae 
Typical Analysis of Enamel Oil 
speciii¢. Gravity. a. =i aan .9678 
lodine Value; 40 — = 2ares ike = 
Saponifivation Value......... 195.0 
Acid Vali¢ << ese eee ee ie 


PERILLA OIL 


_ Perilla oilis produced in the Far East, in Northern China 
and in Japan. It is quite probable that the seeds trans- 
planted to the United States would grow in latitudes some- 
what above that of the semi-tropical zone, and by selection 
it probably can be made to grow and yield very profitable 
crops as far north as Canada. 

Up to the present time very little perilla oil is used as 
compared with either China wood oil or linseed oil, but 
those who know how to manipulate it, and those who have 
studied its remarkable characteristics have found that it 


LINSEED .OIL 189 


is superior in many respects to linseed oil, and that when 
mixed in suitable proportions with fish oil and soya bean 
oil, it makes a most durable paint. 

As far as its use for making long oil enamel is con- 
cerned, unlike the stand oil enamels of both Europe and 
America, it produces better results and does not turn 
yellow in the dark as quickly as linseed oil or China wood oil. 

Exposure tests have shown that this oil is equal and 
in many respects superior to linseed oil. It polymerizes at 
temperatures above 260° C. and when thickened at too 
high a heat, it makes a colloidal solution with petroleum 
distillates, and not a genuine solution, so that, if petroleum 
distillates are to be used in thinning perilla oil, it must 
first be dissolved in turpentine and 10 per cent of benzol, 
and then the petroleum distillates can be added without 
fear of separation. 7 

The constants of perilla oil are similar to those of linseed 
oil with the exception of the iodine value. Any good stand- 
ard perilla oil would have an iodine number above 200. It 
is the only drying oil which has this high iodine number. 

The following is a fair average indication of the constants 
of perilla oil. 


paecr IG GoTAVILY.. Ge... eke se ck ©.9340-0.9350 
BNE AN TICS Bes ae odin Ss ce | 4.1-6.8 
Toren UMDGE, a... kb ee hs oe 201-206 
Saponitication Values. 5. ) cen... 188-195 

er actince Nex, roe Oke oe, Fat I.479-1.484 
OTe ISPersion: ..4, 4% 4 AOR: = ,O10240 


The waterproofing quality of perilla oil is midway be- 
tween that of boiled linseed and China wood oil, and when 
added to China wood oil in the proportion of not over 
25 per cent does not detract from its waterproofing quality. 

When applied too thickly or not thoroughly brushed 
out, it wrinkles and puckers, but this may be overcome 


Igo CHEMISTRY AND TECHNOLOGY OF PAINTS 


by always adding the requisite quantity of thinner, such 
as turpentine or petroleum distillate. It does not take 
as much drier as linseed oil, and in fact, for tropical cli- 
mates where the heat and the ultra-violet light are greater 
than they are in the temperate zone, 4 per cent of cobalt 
drier is all that is necessary for the proper drying of 
perilla oil. 

For the manufacture of table oilcloth and linoleum it 
possesses particular advantages, especially when used in 
conjunction with soya bean or fish oil. 

The odor of perilla oil is similar to that of linseed oil. 


CHAPTER XIV 
CHINA Woop OIL 


THIS oil is also known as tung oil. It is obtained from 
the seeds of a tree which grows principally in China. Very 
little attention is paid to its cultivation, and it is estimated 
that not five per cent of the trees in China are taken care of, 
although any statistical record with reference to China is 
not to be relied upon. ‘The trees, without any fertiliza- 
tion, grow to a height of 30 to 4o feet. They also seem 
to thrive on waste land and rocky soil where there is 
sufficient rain. 

The area in which the tung oil tree flourishes is an 
area between 23° and 33° north latitude, approximately 
600 miles; and from 95° to 115° west longitude, approxi- 
mately 1200 miles. The same indigenous difference takes 
place in the seeds grown in these latitudes and longitudes 
that there is in tobacco grown in the United States in the 
same relative area. The trees in the South mature quicker, 
but the trees in the North are hardier, so that the Hupeh 
and Szechwan provinces really produce the finest grade of 
oil. The tung oil tree grows in fact as far North as Shanghai 
where there is snow and ice, so that there is no reason why 
the tree cannot be planted in other countries where they 
have cold winters. 

The nuts, produced by the tree, contain three, four, or 
five seeds enclosed in a very dense shell. I have seen nuts 
that have been worm-eaten, decomposed, and in an other- 
wise unsuitable condition for pressing. Very little care is 

Igt 


CHEMISTRY AND TECHNOLOGY OF PAINTS 


192 


NOINAY WO ONAT, SMOHS vaay BHOvIG “£6 ‘ON 





CHINA WOOD OIL 193 


exercised in their selection. The seeds are generally roasted 
over fires to split the outer shell, and whether they are over- 
_heated or under-heated makes very little difference to the 
native producers. 

After roasting, the seeds are ground and are then ready 
to be pressed. The presses, which are similar to the ante- 
diluvian type of Biblical times, are hollowed out of the 
trunks of hard wood trees. The ground cake is placed 
inside and the oil is pressed out by driving in wedges. 
The oil is collected in wicker baskets that are paper-lined, 
and dead animals, insects, and other offal frequently find 
their way into these baskets, although more care is exer- 
cised at present. This is one of the reasons why there 
has been so much difference in the constants of China 
wood oil. The adulteration with other oils which are much 
cheaper than China wood oil also made a great difference 
in the material that has been shipped to foreign countries. 

The actual chemical composition of China wood oil will 
probably be established with more certainty than it is at 
present, when a standard shall have been made of oil, which 
is expressed with modern machinery or extracted with 
solvents, from selected nuts grown on fertilized soil. But 
suffice it to say that China wood oil consists principally of 
elaeomargarine, also known as elaeostearine. 

Much of the literature of China wood oil is hearsay, as, 
for instance, the statement that the Chinese have used it 
for thousands of years on junks and other woodwork in its 
raw state. It is probably true that for many centuries this 
has been the principal oil for varnishing or waterproofing 
paper, such as umbrellas, the backs and sides and masts of 
the junks, and wooden floors of compounds. On the finer 
class of river craft, and on table tops and inlaid furniture 
I found that Ningpo lacquer, and a mixture of lacquer and 
China wood oil, was used. 


194 CHEMISTRY AND TECHNOLOGY OF PAINTS 


Another myth that has appeared from time to time Is, 
that Hankow oil is the only good oil produced in China, 
and Canton oil is no good. As a matter of fact, there is 
no such thing as Canton, Hankow or Hongkong oil. ‘These 
cities are simply collecting points, and one might just as 
well speak of Liverpool, Buffalo or Duluth linseed oil. 

The importance of China wood oil in the paint and 
varnish industry may be simply expressed by the fact that 
in 1896 a few barrels were exported whereas in 1924 fifteen 
million dollars’ worth was exported. 

The Chinese merchant is no different from the merchant 
of any other country in so far as he will adulterate any 
product with a cheaper material in order to make additional 
profit. This has led the Chinese to use any oil which is 
cheaper than China wood oil, and at this writing mineral 
oil or paraffine oil is used. This adulterant is about one- 
third the price of China wood oil, and somewhere between 
the pressing of the nuts up the Yang-tse River and the 
delivery of the oil to Hankow or Canton other oils have 
been added in the nature of adulterants and this has done 
the industry and the manufacturer a great deal of harm. 

For years many chemists have been at work standardiz- 
ing China wood oil, and given ample time, it is quite possible 
to determine the purity of any shipment of China wood oil 
within reasonable limits. 

The average constants of China wood oil known to be 
pure all indicate that the oil must have a gravity of at 
least .g40 at 15.5°C., but China wood oil can be pure 
and have a specific gravity of .938. The iodine value will 
range between 159 and 167, the ate tO 190, and the 
acid value from one to seven. 

A great many determinations of the constants of China 
wood oil of known origin and direct importation were made, 
as will be seen in the following pages. An investigation on 


CHINA WOOD OIL 195 


the examination of the same types of oil mixed with s, 
to and 15 per cent of other oils has also been tried. It is 
worthy of note that the heat test alone as indicated in some 
of these samples is not significant, and varnishes made with 
China wood oil adulterated with 5 per cent of many oils 
do not give any immediate indication of admixtures. The 
variation in acid number is a factor in polymerization. 
The higher the acid number, the longer the oil takes to 
polymerize. 

However, from the business standpoint no manufacturer 
wants to buy an oil which is impure, and the tests up to 
the present writing permit the acceptance of oils that are 
not pure. The object, however, of this lengthy and careful 
investigation is to establish a method which shall be quick 
and accurate, and which will indicate beyond peradventure 
that the China wood oil examined is pure or impure. As 
every one in factory practice knows, when a shipment of 
material is delivered, the cost of taking it into the ware- 
house and putting it in tanks while it is being analyzed 
involves labor and expense which is part of the business 
organization if the material is accepted, but if the material 
is impure and has to be pumped out of tanks and re-filled 
into barrels or other containers and shipped back again to 
the original consignee, it adds undue expenses which may 
or may not be refunded. 

It is for that purpose that I am establishing the following 
methods for the testing of China wood oil which are quick 
and absolutely correct. After these tests have been made, 
should further tests be desired, such as saponification, acid 
number, iodine number, polymerization, etc., they can be 
done at leisure, but these tests take a long time, and can 
only be used to establish, ratify and corroborate any previ- 
ous decision. 

It is perfectly possible to adulterate China wood oil 


196 CHEMISTRY AND TECHNOLOGY OF PAINTS 


with 5 per cent paraffin oil so that it will pass the poly- 
merization test, and have the accepted specific gravity, but 
it is very simple to detect the admixture of an oil of this 
kind even though the gravity and polymerization are correct 
if the refractive index and color dispersion are made. 

Specific gravity, color dispersion, and refractive index 
occupy only a few minutes, and when these three con- 
stants agree with the established standard for pure oil, it 
is absolutely positive that all the other constants will be 
in harmony. 

Referring again to the case of the adulteration of China 
wood oil with paraffin oil,! and where the saponification 
test is made, it is easy enough to extract paraffin oil, 
because it will not saponify. When 5 per cent of any oil 
is added to China wood oil, one of the two indicators, that 
is, either refractive index, or color dispersion, will be thrown 
out of standard, and up to now no sample of adulterated 
oil which we have examined gives concordant figures for 
all three of the indicators which I propose. 

The best instrument of the kind is the Abbé type of 
refractometer, an account of which will be found in Chap- 
ter XXXI. 

There is only one wood oil refinery in China. This is 
owned by a Chinese corporation at whose head there is 
an English chemist. All the others are warehouses and oil 
storage plants where the oil is received in baskets, strained 
and placed in tanks where it is heated up to about 105° C. 
and allowed to set anywhere from one week to a month or 
more, depending entirely upon commercial conditions. 


' This was first worked out under the name of the Potsdamer 
method, in the laboratory of Toch Brothers, Inc., Long Island 
City, more than thirteen years ago. See “A Method for the De- 
tection of Adulteration of China Wood Oils,” L. S. Potsdamer, 
Eighth International Congress of Applied Chemistry, Sec. Ve, 1912. 


197 


CHINA WOOD OIL 


"plo sivaA OM} UvY} SSOT “RP SoT]LASoUTeD) 
‘los Apuvs Ul UMOIS “Aaay, TIO ONAY, Nvoraawy °S6 ‘oN 


"VNIHZ) NI AXaXT, TIO ONAT, “vO ‘oN 





198 


CHEMISTRY AND TECHNOLOGY OF PAINTS 





oo 


No. 97. PRESSING THE NUTS IN PRIMITIVE FASHION. 


CHINA WOOD OIL 199 


The foots or sediment are returned to the original 
Chinese shippers and not paid for, and this oil finds a ready 
market among the Chinese for waterproofing various fabrics 
and for the varnishing of junks. 

The Chinese are exceedingly apt in heating tung oil 
in little earthenware dishes at low temperatures, principally 
not over 125° C., and it is kept at this temperature until 
the oil thickens slightly. It is then applied by means of 
either a stiff brush or rubbed on the wooden surface of the 
junk and scraped off. In this manner many coats are 
applied. 

For the varnishing of floors, in China in some of the 
private houses, called compounds, the floors are most 
beautifully polished. A small amount of Ningpo Varnish 
is added to the wood oil. 


A STUDY ON THE REFINING OF CRUDE CHINA 
Woop OIL 


Crude China wood oil is turbid and has a yellow 
color and a characteristic odor. The two samples of crude 
oil taken for this investigation were received direct from 
Hankow. They show the following constants: 


Pacopeenic; Gravity (60° F.) 2.0. ea: ©.9399 
Refractive Index (21.5° C.)..:... Tec t7G 
Dispersion Value (21.5°C.)...... 0.02025 
eatebest* (Browne S)ec\.... 6. 2%; I1+ min. 

Pe peciuic Gravity, 0 i) 62) Fp 0.9408 
Refractive Index (21.5° C.).:.... 15176 
Dispersion Value (21.5° C.)...... . 0.02032 
Heat Test (Browne’s)............ II min. 


Three general processes of refining the crude oil were 
tried in the laboratory: 


200 CHEMISTRY AND TECHNOLOGY OF PAINTS 


1. Heating 
2. Oxidation 
3. Adsorption 


The procedure for each experiment was varied in order 
to find out under what conditions the best result could be 
obtained. However, in each case two hundred grams of 
oil were treated in a beaker having a capacity of 400 c.c. 
The exact manipulation and the effect of such treatment 
upon the constants of the original oil will now be described 
carefully: (from (a) to (d) refer to crude oil No. 1; and 
(ce) and (f) refer to crude oil No. 2). 

(a) 1 per cent of barium peroxide, mixed with 50 c.c. 
of water, was added to the crude oil. The mixture was 
then heated up to 90° C., when dilute sulphuric acid was 
added drop by drop to evolve the oxygen from the barium 
peroxide. The oil, after such treatment, was poured into 
another beaker. One per cent of powdered pumice and 1 
per cent of Fuller’s earth were then added. The mixture 
was again heated to 105° C. and agitated for 30 minutes. 
The oil was not clear after filtration and on further stand- 
ing the white precipitate increased. Upon examination, it 
had the following constants: 


specific: Gravity (007 Pie. octen ee eee ©.9399 
Refractive Indexer 3502) ae ee t 5177 
Dispersion) Value*(ar5> Gay ee 0.02039 
Heat Test (Browne's), eae ee Tox min. 


Whenever crude China wood oil is treated with barium 
peroxide, the oil is bleached; but it does not remain clear 
on standing. This is probably due to formation of an 
insoluble barium compound, resulting from the chemical 
reaction between barium peroxide and the oil. 

Flashing is liable to take place when barium peroxide, 
without the addition of water, is heated up with the oil. 


CHINA WOOD OIL 201 


This can be avoided by first bringing the oil up to a high 
temperature, and then dropping in the barium peroxide. 

(b) The oil was treated with 2.5 per cent of an activated 
carbon. The mixture was heated up to 105° C. and stirred 
for half an hour. After filtration, the oil was clear and 
bleached to a certain extent. The constants of this oil were: 


PectimemaravirvedG0 I.) icp. Range ts: 0.9405 
io mrocuve Index-(2t.5° Cock ee ee. Pasl7S 
Pispemion. Value (eres Co) oe we. 0.02048 
Freatelesty Browne Sles. hee sh. ee tacts va 10s min. 


A peculiar chemical action was observed,— that the oil 
which was treated with an activated carbon began to 
crystallize in four or five days and finally turned entirely 
into a solid white mass. The acid numbers of this oil and 
of the original oil are practically the same, being 8.6 and 
8.75 respectively. The melting point of the solidified tung 
oil is between 51° and 53° C. This solid form is probably 
the glyceride of B-Elaeostearic acid, formed by a molecular 
rearrangement of the liquid form and which is catalized by 
activated carbon. It was first noticed by Cloez that light 
has the same effect of changing liquid tung oil into the 
solid form. 

(c) The crude oil was simply heated up to 200° C. and 
the temperature maintained for ten minutes and finally 
filtered. The oil obtained has the following constants: 


BHCOMGKGITAVILY (OO -sHL) ates «ct qi 0.9420 
Refractive Index (21;75°°C.))o-.... fein toner TesSryo 
Dispersion. Value (ar. 57 Gj oer oe as ©.02000 
Hieat. best CBrowne’S)s..cnts . oats et ae Seo 10x min. 


(d) The crude oil was mixed with 5 per cent of Fuller’s 
earth and heated to 150° C. for fifteen minutes with constant 
stirring. After filtration, a very light colored clear oil was 


202 CHEMISTRY AND TECHNOLOGY OF PAINTS 


obtained. The oil also remains in good condition on stand- 
ing. Its constants may be shown in the following table: 


Specific (Gravity (60 ti2)..2a re eee O.9401 
Refractive Index (or S¢C: 02 eee 1PSL76 
Dispersion Value~2%-54G@.). o) ep ee 0.02053 
Heat Testi( Browne's) 2)... a: eee 105 min. 


(e) For thirty minutes the crude oil was heated up to 
120° C. with 1 per cent bone black. Then it was filtered. 
The oil was clear and bleached to some extent. It had 
the following constants: 


Specific: Gravity (Go 4b) A272. eee ©.9397 
Refractive Index @1.5 C42) ae 1.5176 
Dispersion Value. (21.5° Cj ya eee 0.02043 
Heat Test: (Browne's). 2/253. ee roy min. 


(f) The crude oil was treated with 2 per cent of Fuller’s 
earth and 2 per cent of bone black. The mixture was 
heated up to 120° C. for thirty minutes and then filtered. 
The oil obtained was very pale in color and clear. It 
had the following constants: 


Specific'Gravity (60°. Hat, ae ee 0.9395 
Refractive Index (21.5> C:) fa. ee iE Gis 
Dispersion Value (1.5 CG.) ae 0.02042 
Heat Test: (Browne’s) (:. Resco ee 103 min. 


Many other methods have also been tried in the laboratory 
such as the use of the oxygen liberated from manganese 
dioxide, potassium bichromate, and sodium peroxide. 
Bleaching with sulphur dioxid and chlorine gas did not 
give any striking effect. Among all the methods tried 
bleaching with 5 per cent Fuller’s earth, or with a combi- 
nation of Fuller’s earth and bone black, gave the best 
result. 


CHINA WOOD OIL 203 


EXAMINATION OF CHINESE Woop OIL 


Two samples of Chinese wood oil were used (one from 
J.M.C. and the other from M.A.F. Co.). Each of these 
was adulterated with 5 per cent, to per cent, and 15 per 
cent by weight of the following oils, — paraffin oil, soya 
bean oil, linseed oil, perilla oil, corn oil, menhaden oil, 
stillingia oil, peanut oil, tea seed oil, tallow seed oil, cotton 
seed oil and rape seed oil. 

The specific gravities of the oils were determined by the 
use of a Westphal balance at 60° F. 

A Zeiss Abbé’s refractometer was employed for the 
measurement of the refractive indices, while the dispersion 
values were calculated from the refractive indices and the 
readings indicated on the drum of the compensative prisms 
with the aid of the dispersion table provided for the re- 
fractometer. The temperature throughout the experiment 
was maintained at 21.5°C. 

The following table shows the results obtained for all 
the original oils used in the adulteration of the two samples 
of Chinese wood oil: 


Oil SP. Gr. Ref. Ind. Dispersion 
60° F. Pai des OF PAN sed Oe 
Chinese wood oil J.M.C....... 0.938 I. 5181 0.02073 
Chinese wood oil M.A.F. Co... 0.939 Doers? 0.02074 
Meat Data. Olle. oa. tk 0.874 1.4870 O.O01158 
Bove Dea allie)... oe. ola 0.944 1.4769 0.01027 
Refined linseed oil............ 0.933 1.4796 0.01078 
SEES CH, Soy) eS re ©.940 LeAy53 0.01008 
Eee PiiceOliar ney sce 0.934 1.4821 ©.01062 
08, HAT 0 Oe a ee 0.936 1.4822 O.OIII4 
Be Olas oa oe ie ea «hs 0.033 Lot 713 0.00971 
SLEW EEO TS Bo) ROS ee tee 0.939 1.4816 0.01036 
eepSeeCh Ol 8. a bale he cchon omen) 1.4605 0.00927 
MeO WSCCUAOI sy.) 15. os eek 0.949 1.4860 ©.01092 
Pottonssced? Oiled 7s fete 0.922 I.4720 0.009897 
fee SCE Ol 4a eee. On ge ©.914 1.4734 0.009894 


204 CHEMISTRY AND TECHNOLOGY OF PAINTS 


The following table shows the effect of adulteration on 
the physical constants of Chinese wood oil: 


SAMPLE I. J.M.C. CHINESE Woop OIL 


Oil 


Chinese wood oil alone. ..... 7... 


ar's.le Ke. ene 


oy ) We ooh eb: 


eee ce Pan 


C. W.O. plus 5% paraffin oil... 
Cow. Oe 4204, a eae 
CoWLOee me, 2 et 

COW ON e557 cova pean on 

ClW Ons 0 ‘<“ ‘< 

Gs W.O cc 15% ce (a9 (79 

C W..O.8 ts eo, linseedsoileae 

Ge WO. eet eae a ee Se 
CWO. “Ree. 
C.W.0. “ 5% perilla oil... 
CIW= OF eR o ere ge ee 
CCH ee ee 

Gi Ws OF me is econ. onl eee 

CW Osaercee ae 
CAVEO tC 

C. W..0. 18% menhadensoile.. 
CEWe Ome eetou. oy s 

CW. Ov eS eon eee 
GawsOme Eo siillingiasou sae 

CP We OF rs 7 +. is 
CMON Ne eh 

C. W. OF #2945) Deaniit oleae 
CaWEe OF erero 0 vias a eat ey 
CWiO; it tee eee 


ce) 


Oo Oo 


Ref. Ind. Dispersion 
pay ae 2 8 ates 


LT. 5ISTo. Sos02074 


La! 


5105. -onozorg 
1.5149 0.01964 
J5132 eCmoloas 


e 


1.5160 0.02007 


1.5130 >) OfOlane 
I.5IIQ 0.01920 


1, 5162)>\ oC. O2e07 
¥.5143-) UOno1070 
L S22 20; 0toe. 


1.5103) 10702026 


Te5IA5 2 OnCLg 
LUST 25 Np Ono nose 


1..5150% » 0.02007 


1.5140) 0 s01077 
I SILO sO volpay 


LU5102 4, 0°62628 


1.5130) 0.01077 
I.5115 0.01903 


1.5163) O102020 
1.5146 0.01990 
1. S12% a (0, 0104e 


eI 


. 5158) -0,,02007 
512008 OcObGas 
.5LI4* 0. OT@00 


eS & 


CHINA WOOD OIL 


205 


The effect of adulteration on the physical constants of 
J.M.C. China wood oil is shown in the following table: 


Ref. Ind. Dispersion 
Kae te 


. sp. Gr. 

one GO eter ars peers 
ean) epiise 57, tea seed oll:.>. 2. ; ORO 3o mers SG 
OTe a ee en 01920. 6 1.5135 
Se OT Oe Of095*a Tas 10 

C.W.O. “ 5% tallow seed oil (Han- 
Ky Pemie g fe) faekt OCO41Ts S107 

C.W.O. “ 10% tallow seed oil (Han- 
Kove ierpac fe ya O08) gems SA 

C.W.O. “ 15% tallow seed oil (Han- 
HOW age ho On045Uh T5135 
Gave w. e854, cottonseed oil... . - OnGey aut oS TOL 
eWEOaje elon ee eked seat eis Oh Gk ys @ ay idmcwices 
CAV Ore oT 5G PeRiee ieee Or Gey ete SLT 4 
ee Orme ees, rapeseed Oils. 2... 0;038>- 1.5161 
RN ee oe. 0.930). Te 5129 
eG tee ae? 0.035 1. 5116 
ay ee 8 Sova. bean Gil ($2). 20.938* ~ 1, 5162 
Pay eOesetOl; eh ee OO gS er elerelA © 
a a te Th aay eee heat OF O08 Tp ys LLG 
omy On 5% menhaden oil (52)...0.938 1.5166 
Cee Oe 10% aT ke OO sO teh oT AY 
We Ot 5% é ET EAS EMO 0g comp aweeks) 
SAMPLE II. M.A.F. Co. CHINESE Woop OIL 
Chinese wooo alone. oa os a SRG TSE 
aoe pus. 35%, pataiin-ol. 3... G7025 an I S105 
Pe LO Ay 220s De eee OL0Son) Tasia5 
Ce wWeeO.aee F159 .9 -o ES od on Sp 7 Sie le Sse 
awa sano osoya bean oily x62, G2O30e sea S101 
Mea) toes ls Te eee 02920 a1 e5140 
(Cn, NON G RaSh ate oe ee ee eS O 040 nk 122 


OF 
OF 
Of 


Ono 


oO 


O 


Oo O 


02006 
01970 
01879 


,02013 


.01978 


01949 


.02005 
.O1962 
.O1916 


02026 
.O1982 


.O1925 


.02005 


.O1979 
.O1940 


.02029 
.01978 
.O1922 


.02074 


.02046 
.©2000 
.01967 


.02030 


.O199O 
-O1954 


206 


the physical constants of M.A.F. Co. China 
E: 


O 


ECE SEES. CRACOW PhOnOw ie he MeV Koh ora 


Ce 
ee 
C 


okene 


W. 


Shee ges eine ce 


O. 
ws 
O. 
O 
O 
O 
O 
O. 
O. 
O 
O 
O 
O 
O 
O 
O 
O 
O. 


CHEMISTRY AND TECHNOLOGY OF PAINTS 


Oil 


bous 

plus ts, linseed oil ye, soe e020 
ONT OV bales, baie one ne CRO 
Eh TSO Oh eee ee oO ee 
‘eho petitla oil uta b aeeeee 0.938 
OS TO Gig ks amet ea eer 0.938 
as 15% P Pim Scans ie eee 0.937 
vi-c| OE COR Olle. miter ee 0.939 
f IO Soy SSE eee ee 0.939 
ROT AM Ese 0.939 
“5% menhaden oil, 9.6 0.939 
SEONG Me oe Face 0.939 
6 Lee ee aE IK ot 0.939 
“35% stillingia, Oil come Os a3 
OU CS ee eae 
6c 15% es pe earth. oF 0.937 
"2 LeU WeaNut Olle bake eames 0.939 
ToS, ae te tear a eae 0.939 
Laas; aaa oe 


Sp- Gri 


Ref. Ind. Dispersion 
Oy We Br MSO Nan | 
1, 5102 “Ov02032 
IL. 5141 ~ 0.02004 
I... 5124 4, RO, OLO50 
1.5166 0.02044 
1.5148 0.02004 
I'5130) <QzQreb2 
1.5161. 50.020¢2 
I...51392 Oraloe. 
I. 5110 = 90 .0lec. 
1.5106. > Of07032 
Li 514 fio Osc rege 
1.5120" -Glorgss 
I. S100 .%sO.c2o42 
1.5148 0.01990 
L-. 5130) OL OLQRS 
I.5160 0.02019 
1.5138 0.01990 
1.5112 “4001070 


The following table shows the effect of adulteration on 


O. 
0: 


O. 


O. plus 


onene 


¢ 


5G. leauseedr Ol ay ee ae 0.037 
LOVE" ee Seen ens 0.936 
15% 2 ee ee 0.935 

5% tallow seed oil (Han- 

MEOW i cana! eae re 0.940 
10% tallow seed oil (Han- 

kow) e300 a ee 0.942 
15% tallow seed oil (Han- 

kow) Geer eee 0.944 

5%, cotton secd.ollwwaat 0.938 
LOC Gm be ache e cave Ce 0.937 
ey a Wes 0.936 


Ty 


iE 


lie 


Lea} 


= ee 


wood oil: 

5160” 0, 02017 
.§139-- OnGrogs 
5112 0.01899 
5106 ~ 10, 02012 
»SIhO PO, 01970 
.5140 0.01945 
5162036, 02020 
.5140 0.01990 
, 5119s Beroross 


CHINA WOOD OIL 207 
Sp. Gr. Ref. Ind. Dispersion 


Oil 60° F. 21-5. i thee 
veep iis= 5 rape seed oil....,.. 0.939) 1.5164 © 0.02015 
ere eo tOY,- | een a 01037 eae Te TAC/E O.01000 
Re eS a. 0.035 TeS121- 0.01026 
Seve = 5%, soya bean oil (S2).. 0.939- 1.5166 0.02628 
ever. as TOU,“ eee oerrerOrG ton r Te S144. 1 0.01000 
CeWeOs 15% * aE! ee OS 4 Smeal 61234. OF O10 21 
eee eo, tnenhaden oil (S2):. 0.9030' 1.5168 ~ 0.02033 
net, 10% ‘f On Aco mr S152. 0.01084 
ays ers, . eee meen O.O30) Mt 01228 OL OTO2T 


HEAT TEST OF CHINESE Woop OIL 


Apparatus. — Test tubes, 15 cm. by 16 mm., closed by 
a cork so perforated that a giass rod could move freely. 

A 4o0o-c.c. glass beaker, 10.5 cm. by 7.3 cm., filled with 
soya bean oil to a height of 7.5 cm. 

A nitrogen-filled thermometer of 600° F., placed at 
1.5 cm. from the botton of the bath. 

Procedure. — The bath was heated to 560° F. Then the 
test tube containing 5 c.c. of the oil to be tested was im- 
mersed so that the bottom of the tube was level with the 
lowest part of the bulb of the thermometer. The time was 
noted. The source of heat was so adjusted that the tempera- 
ture of the bath was kept as steady as possible at 540° F. 
When the sample had been in the bath 9 minutes, the glass 
rod was raised at intervals of + minute until the sample 
became gelatinized. The time was again recorded. 

The results obtained from the experiment are shown in 
the following tables: — 
TaBLE I. J.M.C. CuInEsE Woop OIL 


Time in Minutes 


Oil Run 1 Run 2 Average 
Ciinese wood oll alone, ... ...hs..0n. ig ete! THA20 Liye 
ey er piis 5%, paratin: ollie... 12 380 1 ae ae) Le 
eV Oma 8TOUG.. rs bees by cr F23250 120-20 T2040 


og ie ORR S25 5 oy Aaa Soa naana st his ae [5700 fists oo. 


208 


O. 
O 
O 
O 
O 
O 
O 
O 
O 
O. 
O. 
O 
O 
O 
O 
O 
O 
O 
O 
O 
O 


Nel pr. groove. ep euololmc chen tougtoaoiel oe 
Sam re re ge ee 


Oil 


CHEMISTRY AND TECHNOLOGY OF PAINTS 


Time in Minutes 


Run 1 Run 2 Average 

plus 5% soya bean oil..... nea T2220 logge 
pe FO ae ee plea one a 13.7 20 T9hLO L321 
Se Eee Oe eee 14:50 14/230 14 : 40 
‘ite 5 U7: INSEE Ola ee 12:15 12745 2s 
ETO Ug Musa we! ot 14°230 14°20 TA 48 
eo Cs Sie Nast Bereta 16:00 T5240 DS 50 
useo perilla. oll een L210 L2ae50 12:40 
Ty LOWE i cease See ee ae Nee ee Tatas T2eaS 
RON te eR I cc ve) ohn 15.210" 2 acy O Eo 20 
Hy iS Ce eCOT TCO Loa a eran Leto 13:40 [3;. 30 
OT TOU al ee ee ee TAs Iqi2s 14.728 
TS One one ee ee 16:20 16:10 TOgae 
oe 505 menhaden-onl sae Toes 124520 13-218 
LOU os Chsscees Rew ee. 14.210 1Al Od 
aR, - : 14 : 40 14 50 14:45 
‘-'s@, stillingia oul ge = ta seco P2520 12 Os 
ior, es Mea ac ORIG i3°s0c 12:50 
tke a7, be i ie bse 13:40 nee 
5 7G. DEAT Oh einc te ices I2 :00 Tiea5o Tiss 
CN TOGG aS ac ean atee eee E320330 E3026 Lass 
oT 5 Oe hn sh eed ee eee 14.345 142350 14:48 


HEAT TEST OF CHINESE Woop OIL 


Chinese wood oil alone 


Gwe Ocplus 
GaWw20ss- 


Oil 


5% tea seed oil 
10% c¢ (7 ¢ re 


15% 


5% tallow seed oil 
TOU, 66 (95 66 


157% 


a3 (<3 66 


c 


See 
sae 


Time in Minutes 


Run 1 Run 2 Average 
IO : 10 TOR2O Io -15 
Il } 40's 21 ce eee 

120 D2 FO P25 

[10:14 eC ei taeat 
a Se Ke, LT. 2200s Lise a 
Lisesc Li 407 fees 
I2 :00 12555 12.53 


CHINA WOOD OIL 209 


Oil Time in Minutes 
Run 1 Run 2 Average 
2): fas 5% Sh g08 SCOGLOlLer a. EOuceys al tes II :00 
10% be Ea ye Tes OO Maio elo Tao c 
met Svgo. ROR? ip col oS Tere sR lien RC ARES &) 
Maes Golapersced Oll. .;. ae Tly) 00s 1L 00% 11:00 
ero i rete he TeV EO) A220. WT Vhs 
oe a eee TAL, OOM so T3650) a 1315.25 


By poova pean Ol (52). wietis; TO» 10°)55° > Tr 33 
ee TOC 2 ee eT 2 LG eet ks es Toe TS 
TE pier eet To SO Perse 4O B13 kAS 


See 8 17, Hee oy albedo aye boa ks etetta me me Beats Li9:,00 
errto Pe are hors) art Chas TEAR 
Beets Uy, 2 ie eer AO To. Oat oe 4c 


eiedel deleWe: Sevouei Nero 
Sae 882 2225 228 
Siler mre. che: Letiede aay oe 


TABLE II. M.A.F.Co. CHINESE Woop OIL 


Oil Time in Minutes 

Run 1 Run 2 Average 
Chinese wood oil alone............... TOr30 TOr40 EOune § 
ewe). Dus 5% paraffin oil.. Fatt410 Leese 20 T2930 
CaWe @. LOS ioe re rhcasiece A WBS Xe) vik iis seb ee 
Cie Ore) 51S) Bee hee Set IO I5 :20 ThetoG 
Pave oes, soya beanioll:. PTs 320 TT 210 a ats 
ers LOU peta Mile ake Cath 1 2eaES 122200 romeo 
eNO a tS 9, eA, ede ras Pee AO P2540 Loman 
eens oes 7, linseed: Ola. . os TP Gro Tease S (isi 
CN OO e979 Sate a 2d oh, py 2. 2 220 1p Bis [26.20 
PR Ome GOL, 2S Sie a 1255.50 T8240 T2015 
eave ee ene Or Herilla Ol tess oo TIa820 ieas4 i143 27 
NUON) Mater eT OO), (2 wie So Wr Seats cs a Ton0 Cats eats 
er) ties eo Cig gas tle is 2 EE ECTS Tazo. ebook ee 
MeV oO) tye os 7, COT Cll er Sen cee a Tie 30 ise is rim 30 
eye Otek NTO tet lant ger T2400 Toe30 Fon20 
PONV AC ees Teo ilies eee ek eee ee fe Means, ict 


ZO 


Chinese wood oil alone 


Chae e eho onene 
paves eopes roles Foes 


Ue eigen euetels. Cini ol enone = Guone 


Seeing oes Fe ee ee lee re a 


O. pl 


SIMO CO OOO OrS Oma Otol 


CHEMISTRY AND TECHNOLOGY OF PAINTS 


TABLE II. 


‘ 


us 
‘ 


Oil 

.O. plus 5% menhaden oil..... 
O; oe 107% “ Gh eae 
Fe rais oe de LN exes 
QO. 320 69, stillnigias one 
O ESa 109 nee Seem 
COE Shea AD ay Sata 
OS) 5%, peanitt Oller ee, 
Ono! 10% ae ee eee 
Ops SanS Oe ae eee 


Oil 


5% tea seed oil 


109 eh se 
15% c¢ 4 bg ARON 2) 
5% tallow seed oil .... 


10% a3 iz ee 


15% (9 a9 ¢ 
5% 


cotton seed oil 


©, Se! "6, le: To wees 0b te) 2 On Re 


Run 1 
Ile 50 
12720 
13/230 
Tienes 
12:00 
ibe tae: 
12 :00 
13:00 
14:10 


ree 


10% c¢ c¢ c¢ 
15% (73 (a3 66 
5% Tapersecd oll oye nuns 


10% a3 (73 (<3 


15% cc ce ce 
576 


10% 


15% 66 6 (a3 6c 
570 


1o07 (5 Co 2S 


6¢ 6c “ 
157% 


“ ce 6 6¢ 


soya bean oil (S2) ... 


menhaden oil (S2) ... 


Time in Minutes 


Run 2 Average 
Tf 5145 Li fAy 
123320 12.2725 
eer ke) benzo 
Eis II =\10 
FO Taree 

Lasgo Porro 
tenn Taye 

13-510 Heras 

LAS co 20 


147 


M.A.F. Co. CHINESE Woop OIL 


Time in Minutes 


Run 1 Run 2 Average 
QO 2 50..a1Or ca O-L SS 
Il $30 “Milgs2Ge eee 
LI 2 §0 S12 ees 
13 3 30 8 13) Soe eee 
TI) EO 4 Pires Bo 
Il 320: Sif 25 eer 
Il 335 9) Ae Ao eee 
10 715 10125 eeowees 
Il 15 ° tg O yee 
13 {10° [2 gle) eee 
10 3 35° TOu eh eae hee eee 
li 55 eee 126.00 
13° 30° See eee 
IO: 40 #2 1Os 50m a erGuee: 
I yy sereje eo? 
1 20°: TOs Oseeet ae 
10:45 10); 30euetopeto 
[I 130° +40) 940 ee 
12 3°30 ~°12 Doh ere 


CHINA WOOD OIL PTT 


HEAT AND QUALITY TEST OF CHINESE Woop OIL 


By R. S. Worstall’s Method 


One hundred grams of the oil was placed in a porcelain 
casserole, having a capacity of two hundred and ten cubic 
centimeters and an average diameter of three inches. This 
was set on a wide-flanged tripod which had an opening 
approximately the size of the casserole. The oil was 
at first heated rapidly with a full Bunsen flame and 
stirred with a thermometer of one-inch immersion. When 
the temperature reached 540° F., the flame was turned 
down and the temperature maintained as near 540° F. as 
possible, until on lifting the thermometer the oil dropped 
with a pronounced string. The time required after reaching 
540° F. until stringing, was recorded as the time of the heat 
test. For pure tung oil the time limit is approximately 
eight minutes. 

As soon as the oil dropped with a pronounced string, the 
flame was removed and the oil stirred with a stiff spatula 
until it became solid. After one minute the jelly was 
turned out and cut with a dry, clean spatula for the quality 
test. Pure tung oil should give a dry non-sticky jelly 
which can be cut like bread and crumbled under the applied 
pressure of the spatula. 

The following data are results obtained from experi- 
ments performed according to the above procedure. — 


Taste I. J°-M.C. Carma Woop Or, 


Oil Time of Heat 
a Test in Minutes Quality 
J.M.C. China wood oil alone aE aRO Dry,non-adherent, cut 
welland crumbled well. 
C. W. O. plus 5% paraffin oil 8 : 40 Dry non-adherent, cut 


wellandcrumbled well. 


212 


O° 
Se ee Oe at ae 


CHEMISTRY AND TECHNOLOGY OF PAINTS 


QO; 66 


Oil Time of Heat 
Test in Minutes 


.O. plus 10% paraffin oil 


TSG (¢ a3 


5% soya bean oil 


10% c¢ ¢é (a3 


ce ce a3 
15% 


5% linseed oil 


14 iz ce 
15% ¢ ce 


5% perilla oil 


10% (<3 (73 


15% ‘< 73 
5% corn oil 

10% ¢ 66 

15% ¢ 6¢ 


5% menhaden oil 


9 


IO 


IO 


IO 


II 


Io: 


iIK®) 5 


Wal 


35 


730 


: 50 


: 40 


: 40 


mp 


> OO 


Xs. 


: OO 


Toh 


5 AS 


Quality 
Slightly softand sticky, 
cut and _ crumbled 


fairly well. 

Soft and sticky, cut 
poorly and non-crum- 
mable. 
Dry,non-adherent, cut 
welland crumbled well. 
Slightly softandsticky, 
cutand crumbled fairly 
well. 

Soft and sticky, non- 
crummable,cut poorly. 
Slightly softandsticky, 
cutandcrumbled fairly 
well. 

Soft and sticky, cut 
and crumbled poorly. 
Soft and sticky, non- 
crummable,cut poorly. 
Slightly softandsticky, 
cutandcrumbled fairly 
well, 

Slightly softandsticky, 
cut and crumbled 
poorly. 

Soft and sticky, non- 
crummable, cut poorly. 
Slightly sticky, cutand 
crumbled fairly well. 
Sticky, cut and crum- 
bled poorly. 

Soft, sticky, cut poorly, 
non-crummable. 

Dry, non-sticky, cut 
and crumbled fairly 
well. 


CHINA WOOD OIL 


BC ele er 


Z 


Ww, 


258 
Oil Time of Heat 
Test in Minutes Quality 

.O. plus 10% paraffin oil On25es Dame ass 595° *men- 
haden oil. 

Oar = 15% ae eek TO.4tO — Soit, sticky and non- 
crummable. 

Ogee) 59, Stillingia oil 8:35 Dry, non-sticky, cut 
and crumbled well. 

re TO, oi fi g:10  Slightlysticky, cutand 
crumbled fairly well. 

eee 5 87, e ‘3 TOS mmole sticky «cut. and 
crumbled poorly. 

Gee 7, peanut oil g:00 Slightlysoftandsticky, 
cut and crumbled 
fairly well. 

Ces a TOU. a 9:20. 4 Sottsand =<sticky, cut 

iy poorly, non-crumma- 
pies 

Cre ere ie. os ¢ 10:13 . Very soft and sticky, 
cut poorly and non- 
crummable. 

et eeors, tea sseed. oil 9:25 Slightly sticky, cutand 
crumbled fairly well. 

Oa meron 10:48 Same as 5% tea seed 
oil. 

Oreo ae 12::8 Very soft and sticky, 
cut poorly and non- 
crummable. 

O. “ 5% tallow seed oil 8:32 Dry, non-sticky, cut 
and crumbled fairly 
well. 

Cli eno ts 8:35 Slhghtlysoftandsticky, 
cut and_ crumbled 
fairly well. 

i ahs Oe, 8 ao 9:25 Soft and sticky, cut 
poorly and crumbled 
poorly. 

O. “ 5%cottonseedoil g:10 Slightlysoftandsticky, 


cut and crumbled 


poorly. 


214 


CWE: 


CHEMISTRY AND. TECHNOLOGY OF PAINTS 


cc 


Oil 


Time of Heat 
Test in Minutes 


ce 


.O. plus 10% cotton seed oil 10: 45 


AI Be 5 [22.5 
5% rape seed oil 0.7 30 
Oops oe 10:50 
15% 66 a cc 12 330 
5% soya bean oil 328 
(S2)! 
10% soya bean oil IO 345 
(S2) 
15% soya bean oil 1210 
(S2) 
5% menhaden ou Guna 
(S2) 
10% menhaden oil 10 210 
(S2) 
15% menhadén ‘oil ya een7 
(S2) 
TABLE II. 


Oil 


Time of Heat 
Test in Minutes 


M.A.F. Co. China wood oil alone Weve) 


C. W.O. plus 5% paraffin oil 9:8 


1 (S2) 2nd sample. 


Quality 

Same as 5% cotton 
seed oil. 

Very soft and sticky, 
non-crummable, cut 
poorly. 

Slightly softandsticky, 
cutand crumbled fairly 
well. 
Soft, sticky, cut and 
crumbled poorly. 
Very soft and sticky, 
cut poorly, non-crum- 
mable. 
Slightly sticky and soft, 
cutand crumbled fairly 
well. 

Same as 5% soya bean 
oil. 

Soft and sticky, cut 
and crumbled poorly. 
Slightlysoftandsticky, 
cutand crumbled fairly 
well. 

Same as 5% Men- 
haden oil 

Soft and sticky, cut 
fairly well, non-crum- 
mable. 


M.A.F. Co. Cutna Woop O11 


Quality 
Dry,non-adherent, cut 


wellandcrumbledwell. — - 


Very slightly soft and 
sticky, cut and crum- 
bled fairly well. 


a= 


CHINA WOOD OIL 216 


Oil Time of Heat 
Test in Minutes Quality 

.O. plus 10% _ paraffin oil 9:55 Same as 5% parafiin 
oil. 

PA) ees 57, 3 es TOs45 ole and sticky. cut 
poorly and non-crum- 
mable. 

pie 5%, Soya: bean oil yen Dry,non-adherent, cut 
and crumbled well. 

AOS ee ae ae goes 9:45 Slightlystickyandsoft, 
cutandcrumbled fairly 
well. 


ese eal Soo! bisteby LOrsson a orsancesticky. cut 

poorly, and non-crum- 

; mable. 

BO) ees linseed oll 9:00 }§©6Very slightly soft and 

ae sticky, cut and crum- 

bled well. 

BileewmetOo% © to:10 Slightly soft and sticky 

cutandcrumbled fairly 

well. 

OMe Sos inn. ED, SO) DOlte and: Sticky -actit 

and crumbled poorly. 

gee eos 7, petilla.oil 9:20  Slightlysoftandsticky, 
cutand crumbled fairly 
well. 

BO ee TOUR! sn 10:22 Sticky and soft, cut 
poorly and non-crum- 
mable. 

Orie i 5 eee I1:00 Sameas1o%perilla oil. 

OF i 357,-corn. oil Op 200 Me oHol tly Metickey Ma eut 
fairly well, non-crum- 
mable. 

Ry Mee TOO G a a TOM. 00 4 POOLl- dandy Stick Vewcut 

poorly, non-crumma- 

ble. 

01 OOP LEER ae od aah aae 11:00 More soft and sticky 

than 10% corn oil, 

cut poorly and non- 
crummable. 


216 


O 
ae GD sees 


W. O. 


CHEMISTRY AND TECHNOLOGY OF PAINTS 


ce 


Oil 


W.O. plus 5% menhaden oil 


10% (a9 ¢¢ 


ee a9 6c 


5% stillingia oil 


10% ce ce 


1507, cc (a9 


5% peanut oil 


109% 6c (a9 


15% (a3 ‘c 


5% tea seed oil 


10% 6c 66 a9 


a3 a3 6c 
157% 


5% tallow seed oil 


10% 6c 6c 6c 


8 


Io 


IO 


ea 


LOv 


Io 


TI 


8 


Time of Heat 
Test in Minutes Quality 


: OO 


- IO 


45 


> OO 


232 


215 


Io 


- LO 


a1s 


45 


20 


*55 


Dry, non-sticky, cut 
and crumbled well. 
Slightly sticky and soft 
and crumbled fairly 
well. 

Soft and sticky, cut 
poorly, non-crumma- 
bie. 
Slightlysoftandsticky, 
cutandcrumbled fairly 
well. 

Same as 5% stillingia 
oil. 

Soft and sticky, cut 
poorly, non-crumma- 
ble. 
Dry,non-adherent, cut 
and crumbled well. 
Very slightly soft and 
sticky, cut and crum- 
bled fairly well. 

Soft and sticky, cut 
poorly and non-crum- 
mable. 
Slightlysoftand sticky, 
cutandcrumbled fairly 
well. 

Soft and sticky, cut 
and crumbled poorly. 
Same as 10% tea seed 
oil. 
Dry,non-adherent, cut 
and crumbled well. 
Slightlysoftandsticky, 
cutand crumbled fairly 
well. 


.O. plus 15% tallow seed oil 


CHINAS WOOD -01L 


Oil 


5% cotton seed oil 


10% a9 6c 6c 


6c 6c ¢¢ 
15% 


5% rape seed oil 


10% 6¢ “ 6c 


‘6 ‘< We 


157% 


5% soya bean oil 
(S2)? 
10% soya bean oil 


(S2) 


15% soya bean oil 
(S2) 


5% menhaden oil 


(S2) 

10% menhaden oil 
(S2) 

15 menhaden oil 
(S2) 


1 (S2) 2nd sample. 


217 


Time of Heat 


Test in Minutes 


9:34 


9 


Io 


Il 


IO 


I2 


IO 


15) 


LOS, 


apes 


45 


:48 


35 


= 30 


ges 


oH 


ols 


; OO 


OO 


IO 


Quality 

Soft and sticky, cut 
poorly and non-crum- 
mable. 

Very slightly soft and 
sticky, cut and crum- 
bled fairly well. 

Same as 5% cotton 
seed oil. 

Soft and sticky, cut 
poorly, non-crumma- 
ble. 

Slightly softandsticky, 
cutandcrumbled fairly 
well. 

Slightly softandsticky, 
cut and _ crumbled 
poorly. 

Soft and sticky, cut 
poorly and non-crum- 
mable. 
Dryandnon-adherent, 
cut and crumbled well. 
Very slightly soft and 
sticky, cut and crum- 
bled fairly well. 

Soft and sticky, cut 
poorly and non-crum- 
mable. 


Slightly softandsticky, 


cutand crumbled fairly 
well. 

Same as 5% men- 
haden oil. 


Soft and sticky, cut 
and crumbled poorly. 


218 CHEMISTRY AND TECHNOLOGY OF PAINTS 


THE PRODUCTION OF TUNG OIL IN AMERICA 


It will be seen from the foregoing that the archaic 
method of collecting the seeds from trees that receive 
no cultivation or attention whatever produces variable 
oil, and that for the further reason that the nuts are 
allowed to rot and split, and then heated without any 
care as to uniform temperature. Many of our scientific 





No. 98. Tune Or Nuts, grown in Gainesville, Fla. These cultivated nuts 
are about twice the size of the Chinese uncultivated nuts. 


statements are not to be relied on excepting or eta. 
particular sample examined, owing to the conditions of 
manufacture. 

For fifteen years experiments have been made in an 
attempt to grow the tung oil tree in the United States, and 
to find a suitable climate for its propagation. ‘There is no 
doubt that below Jacksonville in Florida any species of 
wood oil tree will prosper. There is no question that by 
obtaining seeds that grow in Hupeh and Szechuan Provinces 
which are 30° North, trees can be grown which will prosper 
in Tennessee, Georgia and the Carolinas, but for the present, 
Florida will give us a large quantity of oil, and a private 
corporation (Benjamin Moore & Co.) is planting between 
2500 and 3000 acres adjacent to the plantations of the 
American Wood Oil Corporation. 


210 


OOD OL 


Yr 


a 


CHINA 


VAINOT J 


‘SONTIGHAS ONIINVIG ‘OOI ‘ON 





VaINOTy ‘ATX, GIO AUVAA ANO *66 “oN 





220 CHFMISTRY AND TECHNOLOGY OF PAINTS 


It is very interesting to us that the oil produced from 
the seeds in Florida have different characteristics from the 
Chinese oil, but this is to be expected by anyone familiar 
with the transplanting of indigenous plants. 

Tung oil produced in Florida in 1924 has the following 
characteristics and constants: 


PERCENTAGES OF Ort IN MEAT! (BY EXTRACTION) 
64 PER CENT 


CHARACTER OF OIL PRESSED FROM MEATS 


Color: very pale — almost water white. 


Specitic: pra vity a5 35) faa ee ee 0.941 
Acid value:in aleohal-benzoly ae 5 eer 0.0 
saponification Valueen 1 eet nase eee 194.3 
Todine value (half-hour, Wijs)............ 166.6 
Refractive index. at 35 C3 ee a ee Li5i93 
Browne heat test (A.S.T.M.) — minutes... 9% 


Fruits from S. Tarnok (Augusta, Ga.) 


CHARACTER OF OIL PRESSED FROM MEATS 


Color: very pale — almost water white. 


Specific gravity-at 15.5 Gate, peeesereee °.940 
Acid value in alcohol-benzol.............. 0.0 
Saponification=valueys7 2 sua eee 195.0 
Iodine value (half-hour, Wijs)............ 165.6 
Refractiveindex a25 (Ce ae re eee 1.5188 
Browne heat test (A.S.T.M.) — minutes... 93 


SAMPLE OF AMERICAN TuNG OIL? 


General appearance: golden yellow in 

color and very clear. 
Specific :oravity (sete (oe) nee 0.941 
Retractivesindexn( ois Gy one ton cia I. 5195 


1 Circular No. 195, “Amer. Tung Oil Culture,’ Henry A. Gardner. 
* Analyzed by Dr. T. T, Ling, Research Chemist. 


CHINA WOOD OIL 221 


Peepersion, Valle (o5".G,) oo set: ey 0.02129 
Acid Number in Alcohol-Benzol......... peie 
Iodine Number (one hour Wijs) ........ 175 
BPaPOMMICALON VAlUEs Msc ken ks ok A on. 195.5 

Feats best (100 em, Worstall’s) 2). )/2,. 62 minutes 


The gel is very pale in color, dry and firm; cut and 
crumbled very well. This sample is pure tung oil of ex- 
ceptionally good quality. 

One half of this sample was sent to Dr. Z. Z. Zee at 
Columbia University whose analysis of this oil is as follows: 


Color: very light amber. 
Odor: faint but characteristic. 


SO) LeU ee a eae i 0.9428 (at 15.5°C.) 

Per elaldere yr eek 4 Te5204at 25" Cy) 

PITS METAION exe C2 aig ees 0.02068 

yental DSie noe. NP Aah Gare le, 

POC IMCMNO Ss eS is cts 174 

Heat Test..............  9#minutes (Browne’s Jelly 


test, heating at 282° C.) 
“The quality in my opinion is excellent.” 


When Havana tobacco from the Vuelta Abajo district, 
which is acknowledged the finest tobacco in the world, was 
transplanted to Connecticut and Wisconsin, totally different 
tobacco was produced which did not even appear like the 
original, and yet, from the coarse strong tobacco which was 
originally produced in Connecticut that sold at a few cents 
per pound, by selective transplanting and proper fertilizing, 
tobacco is being produced which commands as high, and 
in some instances, a higher price, than the original Havana 
tobacco. The transplantation of the French grape to 
California produced a wine twice as strong in alcohol as the 
original. Chinese cotton differs from the Egyptian and 
American cotton. Any indigenous plant transplanted in 
various parts of the world becomes either better or worse 


222 CHEMISTRY AND TECHNOLOGY OF PAINTS 


than the original, but it usually has an entirely different 
taste, flavor, or characteristic. It is quite natural, there- 
fore, that tung oil grown in America will be different from 
tung oil grown in China, and, from present appearances, 
it will be an oil that is going to be much more uniform and 
paler in color than anything grown in China. New formulae 
and methods will have to be devised, as the American oil 
polymerizes more rapidly and the addition of organic acids 
or possibly fatty acids in conjunction with rosin may have 
to be adopted in order to extend the time of polymerization 
or prevent it entirely, if possible. 

Unless China wood oil varnish is heated in a kettle 
above 260° C. and kept there without polymerization, the 
resulting varnish will only be good in the summer time but 
not good in our or in other winter climates, for instead of 
drying with a high gloss it flats selectively, and the only 
prevention for the flatting of China wood oil where it is not 
wanted, is to heat the oil without polymerization to a 
sufficiently high temperature and keep it at that in the 
presence of organic acids. Fatty acids of linseed oil and 
rosin are best adapted for the purpose. 

The standard method for making wood oil varnish in 
the case of rosin, is 100 pounds of rosin to 400 pounds of 
wood oil, but in the case of rosin ester, the standard formula 
is 150 pounds of rosin ester to 400 pounds of wood oil. 


DEODORIZATION OF CHINA Woop OIL 


It is possible to deodorize China wood oil and rid it 
of its pernicious characteristics, but up to now it has not 
been possible to do this on a commercial scale, for there 
are many difficulties that arise in any process which 
attempts to extract the material that produces so-called 
“heathen smell.” 


CHINA WOOD OIL 223 


China wood oil as grown in America has a very pleasant 
characteristic odor because the nuts are not allowed to rot 
and no decaying animal matter can possibly find its way 
into the American material, but on the Yang-tse River 
it has become essential to strain the oil as it is poured out 
of the baskets, through iron wire gratings in order to rid it 
of any foreign matter, including dead animals. 

Starting out with the assumption that the odor is pro- 
duced by some material which has an analogy to butyric 
acid or a butyric compound, a large number of samples 
of oil were heated up to 150° C. and nitrogen and other 
inert gases were bubbled through them. In every case a 
reduction of the odor was noticed, but after the oil cooled 
and was allowed to stand in the light, it changed from a 
colloid to a crystalloid and, at first, fine crystals began to 
float around in the oil until, after 48 hours, the oil had the 
appearance of a soft wax. 

A large number of experiments were tried, adding 
materials of carbonaceous nature, heating and blowing 
the oil at the same time, and after filtration the oil became 
crystalline, and in every instance this condition rendered 
it unsalable. Air, steam and some of the inert gases pro- 
duce good results but the oil undergoes a change. This 
work is worthy of further study and experimentation. 


LUMBANG OIL 


This oil will be suited for paint purposes as soon as care 
is exercised in the collection of the nuts, which grow in great 
quantities in the Philippine Islands. As yet, no definite 
statement can be made as to its constants unless a sample 
of oil is extracted from clean nuts, as such a sample will 
differ from the material that is imported into the United 
States at present. It has been used in some considerable 


224 CHEMISTRY AND TECHNOLOGY OF PAINTS 


quantities for the purpose of making putty, but there is 
no reason why it should not be used for paint, as it dries 
well, has a high iodine number, and, in spite of the method 
by which it is handled, it has a low acid number. 

The specific gravity varies from .930 to .940; saponi- 
fication value from 190 to 200; iodine value from 160 to 
170. 

STILLINGIA OIL 


Stillingia oil is obtained from the seeds of stidlingia 
sebifera, native to several parts of China. It is expressed 
from the seeds after the outer shell and mesocarp have 
been removed, and is generally of dark color, due to the 
primitive methods of extraction. Oil of a good pale color 
can be obtained by more modern treatment. 

Tallow seed oil or vegetable tallow is expressed from 
the mesocarp surrounding the seeds. It is also obtained 
by pressing the entire nut, seed and all. This oil, which is 
not-of much interest to the paint and varnish industry, is 
used in China as a substitute for cocoanut oil and tallow 
in the manufacture of candles and soaps. 

Stillingia oil was formerly used only for lighting pur- 
poses, but is now widely used in China as both a substitute 
and adulterant for tung oil. Hard drying, glossy varnishes 
are made of it, 


CHAPTER’ XV. 
SoYA BEAN OIL! 


FRoM 1890 to 1909 the price of linseed oil fluctuated 
between 30 cents and 50 cents per gallon. On a few 
occasions the prices were higher, but a fair average for 
the 19 years was 4o cents per gallon, although in 1896 
it went as low as 25 cents. ‘Toward the end of 1909 it 
rose from 60 cents to 68 cents within two months, 
and in September, 1910, it reached $1.01 per gallon. 
After that it fluctuated between that price and 75 cents. 
Owing to the high price of linseed oil in t910 many 
painting operations were deferred awaiting a lower price, 
or inferior material was used in place of linseed oil. 

The value of menhaden fish oil had already been 
recognized, and while it is admitted that fish oil replaces 
linseed oil for many purposes, it is by no means a true 
substitute. The principal use, however, for fish oil to- 
day is in the manufacture of linoleum, printing inks, and 
certain paints which are exposed either to the hot sun 
or on hot surfaces. 

In 1909 soya bean oil as a paint oil was practically 
unknown. Since that time many investigators have 
published more or less conflicting articles concerning 
soya bean oil, in which even the physical and chemical 
constants of soya bean oil varied to some extent. Owing 
to the fact that discordant results were continually ob- 
tained, it is only within the past few years that it has 

1 Journal of Society of Chemical Industry, June 29, 1912, No. 12, Vol. 


XXXI, by Maximilian Toch. 


225 


226 CHEMISTRY AND TECHNOLOGY OF PAINTS 


been possible to state with some degree of certainty 
whether soya bean oil is a substitute for linseed oil, an 
adjunct to it, or neither. The reason for this uncertainty 
and discrepancy is apparent when it is stated that the 
author himself has experimented with 33 different varie- 
ties of soya beans, while in the records of the Department 
of Agriculture at Washington no less than 280 varieties 
of soya beans are listed. | 

From time immemorial the soya bean has been 
grown in China and Japan, where it has served as one of 
the staple articles of food and as the basis for a number 
of food preparations. In Europe and the United States, 
however, the value and uses of the bean have been but 
little appreciated until very recently (1908), when, on 
account of the scarcity in the cotton seed supply of the 
world, soap and glycerin manufacturers began to turn 
their attention to its possibilities. In Manchuria, where 
by far the major portion of soya beans are grown, 
practically the entire crop is available for export. The 
following figures taken from the Consular Reports will 
serve to show the extent of the soya bean industry during 
recent years: 


1909 IQIO IQII 
Tons. Tons. Tons. 
Total shipments of beans from 
Far; Kast 2a eeyee sare 1,470,870. ~I,200,000 = I, 500;0@0 
Importediinto Hurope = een 400,000 500,000 340,000 


As the above statistics indicate, China and Japan 
retain for domestic consumption practically two-thirds 
of the available supply of beans. The sugar plantations 
in Southern China and the rice fields of Japan annually 
consume enormous quantities of soya beans and bean 
cake as fertilizer, while the extracted oil is used as food 
by the natives. 


SOYA BEAN OIL 224 


In connection with the use of soya beans and soya 
bean oil for edible purposes, it may be mentioned that 
there has been recently established at Les Valées, France, 
a thoroughly up-to-date factory for the production of a 
wide assortment of food products from soya beans. 
Among the more important of these may be mentioned: 
milk, cheese, casein, oil, jellies, flour, bread, biscuits, 
cakes and sauces. According to Dr. G. Brooke, Port 
Health Officer of Singapore, the soya bean, more nearly 
than any other known animal or vegetable food, contains 
all the essential and properly proportioned ingredients of 
a perfect diet. 

All soya beans are leguminous plants, which do not 
tend to deplete the soil of nitrogen, for the typical soya 
bean plant is self-nitrifying and grows in almost any 
soil that contains a reasonable amount of potash. In 
addition to this, the soya bean enriches even very poor 
ground when used as a ground manure. This is done by 
planting the seed promiscuously, allowing it to grow to a 
height of about 6 inches, and then turning it in. In this 
way both nitrogen and potash are given to the soil for 
future use in an available form. The average height of 
the soya bean plant is about 36 inches. The pods 
resemble those of our sweet pea. They. are about 23 
inches in length and are covered with a hairy growth. 
Generally there are two or three beans in each pod. 
After the oil is extracted from the bean the cake 
‘appears to be very valuable as a cattle food, while the 
leaves and stalks, if collected and set in a dry place, 
make excellent silage. We thus have practically the 
entire plant available for use, with the exception of the 
roots. 

The average composition of the soya bean varies with- 
in fairly narrow limits among the different varieties 


228 CHEMISTRY AND TECHNOLOGY OF PAINTS 


of soya beans. In the following table are listed the 
analyses of a few of the varieties of soya beans:! 























| Nitro- 
Variety Water | Protein Fat gen free Fibre || _ Ash 
extract 
Zo %o % Yo Zo Zo 
AUSEIDG, speiae e007 30.50 20.55 24.41 4.00 5.78 
[to"Sate eee 7542 34.66 19.19 27.61 5.15 5-07 
Kingston \2. =. ipo 36.24 18.96 26.28 4.79 6.28 
-Mammoth....| 7.49 32.99 21.03 20.36 4.12 5.8 
Guelph savers 7.43 33.96 Den 72 25.47 4.57 $.85 
Med. Yellow..| 8.00 | 35.54 19.78 26.30 4.53 5.05 
Samarow..... Bie 37.82 20.23 23.65 5-05 5.82 








When the author obtained discordant results from 
the soya bean oil then on the market, the first impression 
was that the oil might have been adulterated, but this 
did not prove to be the case. The oil was, in all cases, 
pure soya bean oil, but from a seed which was not par- 
ticularly adapted for making a paint oil. Through the 
U. S. Department of Agriculture many varieties of seeds 
were received, and through the various seed dealers in 
the United States quantities of seeds of all kinds were 
purchased. The method of extraction followed was to 
grind the seeds very finely in a mill and digest with gaso- 
line in the cold. The solvent was then evaporated and 
the oil recovered. Without going into any lengthy de- 
tails, the percentage of oil extracted averaged 18 per cent, 
and although soya beans range in color from a cream 
white to a jet black it must be noted here that all the 
oils extracted from the various seeds were paler than 
finely pressed linseed oil, and none of them showed the 


' U.S. Dept. of Agric. Bulletin of the Bureau of Plant Industry. 


DOVA SBEAN ‘OLE 229 


chlorophyll extract as markedly as fresh flaxseed. On 
obtaining the various samples of oil it became evident 
why the discordant results were obtained, for some of 
them dried within a reasonable time and some did 
not. 

It has been stated that soya bean oil is not as pale 
as raw linseed oil and belongs to the semi-drying class 
of oils. I must correct this statement; soya bean oils 
made from cold pressed seeds such as Haberlandt, Austin, 
Habaro, Ebony, Meyer, and Ito San give excellent results. 
They have a specific gravity as high as 0.926, with a yield 
fareineeitom«r0 10 19 per cent. Furthermore, a drier 
made from red lead or litharge is unsuited for soya bean 
oil, but a tungate drier, which is a mixture of a fused 
and a precipitated lead and manganese salt of China wood 
oil and rosin, acts on soya bean oil exactly the same as a 
lead and manganese drier acts on linseed oil. In other 
words, a fairly hard, resistant and perfectly dry film 
is obtained within 24 hours by the addition of from 
Butoey7eper cent of this drier. 

Soya bean oil, and when I mention this name here- 
after, I refer only to that suitable for paint purposes, 
ieeeties nearest, oil we have «to linseed, and- under 
the proper impetus of the Department of Agricul- 
ture much of our waste and_ unproductive land 
between Maryland and Georgia, and from the Coast 
to the Mississippi, will yield productive and _ profitable 
crops. The only drawback to the planting of soya 
Pedueise the fact <that it <needs. much. waters: In 191% 
many of the experimental plantings failed on account 
of the drought which was prevalent in the United 
States, but in low marsh land this plant ought to yield 
a profitable crop. It is doubtful whether the soya bean 
would grow profitably in the extreme South. In Cuba 


230 CHEMISTRY AND TECHNOLOGY OF .PAINTS 


the cow-pea, which is analogous to the soya bean, will 
sometimes grow to a height of 20 feet, and form a thick 
mat around the base or abutment of a railroad bridge, 
and that within a few months. This would indicate that 
a soil would have to be selected where the bean would 
not grow to a height greater than 5 feet, otherwise the 
stalks would be too thick and it would be difficult to 
harvest it. Farmers’ Bulletin No. 372 of the Department 
of Agriculture makes the statement that 20 lbs. of seeds 
are required to the acre, and that the production is from 
25 to 4o bushels, each bushel weighing 4o lbs. If this is 
a fact, and since little or no fertilizer 1s needed, yand 
when fertilizer is needed a preliminary crop can be grown 
and turned in to form its own fertilizer, the American 
farmer should be encouraged to try this crop. Fur- 
thermore, in Kentucky two crops during the summer can 
be grown, for some of the soya beans that have been 
tried there have ripened early, and the second crop has 
ripened late, two different selections of seed having been 
used. The statement has been made that soya bean 
could not be harvested properly in this country on 
account of the high cost of labor as compared with that 
of Manchuria and Japan, but this is evidently erroneous, 
in view of the fact that enormous quantities of beans are 
grown in Minnesota for food purposes and harvested 
by machinery. Even in Manchuria the beans are allowed 
to dry and then thrasned out by means of horse power. 
At any rate, if we have any difficulties now with the 
harvesting of a new kind of crop, it is safe to assume that 
with the American inventive genius in harvesting ma- 
chinery, appliances will be invented which will overcome 
this, for the soya business has no greater harvesting 
difficulties than the edible bean. 

Soya bean oil appears to consist of from 94 to 95 


OUy Amp AN OL 24a 


per cent of glycerol esters.t Of these 15 per cent are 
saturated acids such as palmitic acid, and 80 per cent are 
liquid unsaturated fatty acids containing 70 per cent 
oleic acid, 24 per cent linolic acid, and 6 per cent linolenic 
acid. The iodine number of soya bean oil has been 
given as ranging from 121 to 124, but the Manchurian 
cold pressed oil will average as high as 133. 

It may be of interest to show a comparative table 
here between the physical and chemical constants? of 
soya bean oil of known origin lke Manchurian cold 
pressed oil as compared with linseed oil. 


SovA BEAN OIL 

















Name | Color Color of Sp. or, “Acid Iodine 
of seed oil 15. value value 
ey Leer ae Brown 0.9264 0.44 127.0 
PeEANY Yi Black 0.9279 0.14 135.4 
Hiss Straw- | | extremely 0.9234 0.00 129.8 
yellow | | pale 
a eres [ Straw- | 0.9234 OG ee Weg Fite 
| | yellow | | | 
Black, 
Taha olive alee alas 0.9248 0.16 127.0 
saddle 
Straw- soe at 0.9222 0.47 118.2 
Mammoth... deeper than 
yellow 
above 
ae Brown 0.9248 Ons 1209.3 
=) | 
Edward..... ESS med. amber | 9797 ae eae 
| | yellow | | 7 
( same depth 
Shanghai.... | Black as previous, | 0.9241 0.63 Dos 
\ olive tone 
Refined linseed oil .... 0.933 1.0 180.1 








1 H. Matthias and H. Dahle — Arch. Pharm., 1911, 294, 424-435. 
2 Results obtained in the research laboratory of Toch Brothers. 








229 CHEMISTRY AND TECHNOLOGY OF PAINTS 


The specific gravity determinations were made with 
the pyknometer. The iodine values were obtained in 
accordance with Hubl’s method. The iodine values 
indicated are somewhat lower than those of cold pressed 
Manchurian bean oil. This is no doubt to be ascribed 
to the circumstance that the solvent with which the oil 
was extracted was driven off by evaporation in open 
vessels on the water bath, so that the oil became slightly 
oxidized. 

Soya bean oil which is suitable for paint purposes has 
two characteristics which enable the chemist to deter- 
mine whether this oil is suitable or not. In the first 
place, soya bean oil when heated up to 500° F. for a few 
minutes will bleach and remain bleached. Some sam- 
ples which the author has examined have turned almost 
water white. Linseed oil has this characteristic, but not 
to the same degree. Cold pressed soya bean oil made 
from the samples indicated in the previous table, when 
heated to 500° F., and blown with dry air for from 5 to 7 
hours, thickens exactly the same as linseed oil, and 
attains a gravity of 0.960 or over. This is the surest 
indication that the soya bean oil which will thicken 
under these conditions and remain pale is suitable for 
paint purposes. This thickened oil has excellent qualities 
and advantages for making what we call in this country 
“baking japans,” and what are known in England as 
‘“‘stoving varnishes.”’ 

A sample of standard cold pressed Manchurian bean 
oil was heated to 500° F., and blown vigorously for 7 
hours after cooling to 300° F. The following results were 
obtained: | 


SOVA BEAN OIL 233 














Sp. er. Acid Iodine 

60° F. value | value (Wijs.) 
Original oil...... 0.929 2.0 T2310 
Polen eeOlls 08 <2" 0.963 1.9 105.3 











It is interesting to note that the acid value was 
reduced by blowing. The blown oil dried in 3% days, 
whereas the original sample required from 5 to 6 
days. ; 

It appears that the varnish made from a suitable 
soya bean oil bakes very hard and retains an abnormal 
flexibility. As regards the wearing quality of pure soya 
bean oil compared with pure linseed oil for paint, the 
author has had somewhat less than three years’ experi- 
ence, and can only say that it is not quite as good as 
that of linseed oil. A 2-year exposure on a too-foot 
fence gave slightly better results for the linseed oil as to 
hardness and less gloss for the soya bean oil, but a 
mixture of half soya bean and half linseed oil showed 
approximately the same results, while a varnish made of 
25 pen cent of China wood oil with 75 per cent soya 
bean oil gave equally hard results as linseed oil. It is 
too soon to prognosticate the value of soya bean oil for 
exterior painting, but for interior painting soya bean oil 
is the equal in every respect of linseed oil, and particularly 
when treated with a tungate drier. 

Cobalt drier will, under many circumstances, dry even 
those soya bean oils which are not suited for paint pur- 
poses, but for the present cobalt drier is rather too expen- 
sive. It has been stated that from 1 to 15 per cent 
cobalt drier will dry soya bean oil and fish oil. This is 


234 CHEMISTRY AND TECHNOLOGY OF PAINTS 


practically true, but 25 per cent is really needed to get 
the proper drying within 24 hours. Cobalt Tox 
Tungate' is probably the ideal drier for soya bean and 
fish oils. This drier, when present in soya bean oil 
to the extent of from 5 to 7 per cent; ivileidieeee 
latter within 12 hours. 

It is, of course, possible to determine and differ- 
entiate a mixture of raw soya bean oil and raw linseed 
oil, for the iodine values and specific gravities are good 
indications, but when 25 per cent of soya bean oil is 
added to a mixed paint neither the author nor any- 
one in his laboratory can, in all instances, detect its 
presence. 

Blown and thickened soya bean oil is already used 
by a number of the linoleum and table oilcloth manu- 
facturers, and for printing ink purposes it presents some 
advantages. For the manufacture of enamel paints 
heavy bodied soya bean oil produces most beautiful re- 
sults, and as perhaps 95 per cent of all enamel paints are 
used for interior decorative or protective purposes in 
this country its use should be encouraged. 

It-is not within the province of the writer to forecast 
the future of any paint oil, but there is no doubt that if 
a campaign of education be urged among the farmers, 
particularly in those states where soil has been regarded 
as unproductive, and the proper selected seeds of soya 
beans are planted, no scarcity in the flaxseed crop will 
ever again be a menace to the paint and varnish indus- 
tries. At the time of writing linseed oil is quoted at 75 
cents per gallon and soya bean oil at 55 cents per gallon. 
As soon as thousands of acres shall have been planted 

' So called because it was first prepared by the author. It isa 


cobaltic salt of China wood oil. Unless the cobalt is trivalent, it 
will not act as a drier. 


SOYA BEAN OIL 235 


with soya beans, the proper machinery installed, and the 
sale for the cake and the silage arranged, soya bean oil 
will sell at from 25 to 35 cents per gallon, and after the 
ground has been productive of soya beans for some time 
it will be fit for the growing of even the most difficult 
crops. 

Soya bean oil is very much improved by the addition 
of perilla oil, and as soya bean oil is usually very much 
lower in price than either perilla or linseed, it is of consider- 
able advantage to use this mixture when low priced good 
wearing paints are desired. 

For interior flat wall paints where it is essential that 
brush marks should obliterate themselves, Soya bean oil 
is already used to a considerable extent, and for table oil- 
cloth it has been found particularly advantageous. 


CHAPTER XVI 
FisH OIL 


WE are all prone to call all oils of a fishy nature “fish 
oils,’ and the author desires to differentiate between the 
real fish oils and the pseudo fish oils, for there are several 
marine animal oils which have fishy characteristics but 
which are not strictly fish oils, and which do not serve as 
good a purpose as those which are strictly extracted from 
fishes. Some of the fish oils—like cod liver oil— even if 
they were cheap enough, are not totally adapted for 
paint use. The animal oils which have always been 
regarded as fish oils, but which the author calls pseudo 
fish oils, and that are in the market and easily pur- 
chased at a reasonable price, are whale oil, porpoise oil 
and seal oil. All of these oils are by no means drying 
oils, and even if they are admixed with drying oils like 
tung oil and boiled linseed oil, and an additional amount 
of drier added, they are peculiarly hygroscopic, and after 
three months, although these oils may be apparently 
dry, they become sticky when the humidity rises above 
SO. 

The following figures represent some constants of 
fish oils, the specific gravity and the iodine number 
being given in each case. The iodine number is a char- 
acteristic indication of the value of a fish oil for paint 
purposes. 


236 


FISH OIL 231 


FisH O1rLt CONSTANTS 


Specific Iodine No. 
Gravity Hiibl, 


one 4 hours 
No. 1 crude whale oil....... 0.9195 136.1 
No. 1 filtered whale‘oil...... 0.9168 E2520 
No. 2 filtered whale oil...... 0.9187 142.9 
Oe Wet tot ABP ae ls. 0.9196 147.2 
orpoisc body Oil: yu... . 0.9233 132% 
petiole — waterrwhite.. >». 0.9227 143.0 

Menhaden Oil 

atta pieached winter, «). +. 0.9237 150.4 
Ate e te TCTINCC to yc 0.9273 161.2 
hagas Jub Wee“ cele 3 an all ay ai 0.9249 165.7 
PP EROLOWN. cM sa ee ce 0.9250 154.5 


The specific gravities were determined with the aid 
of the Westphal balance. 

The iodine numbers were determined peor dine to the 
standard method ‘of Hiibl. 

The fish oil used for paint purposes is the variety 
obtained from the Menhaden fish, and the winter bleached 
is the variety to be recommended. When refined by 
the simple process of filtering through infusorial earth 
and charcoal its color is that of refined linseed oil, with 
- little or no fishy odor; in fact, in the purchasing of fish 
oil for paint purposes it is well to beware of a fish oil 
that has the so-called characteristic “fishy”? odor. In 
its chemical properties it is so similar to linseed oil that 
it is difficult to differentiate between them. It must 
be observed that oils in mixed paints are not presented 
to the chemist or practical man in their raw or natural 
state, but they have been boiled with driers and ground 
with pigments so that their characteristics are entirely 


238 CHEMISTRY AND TECHNOLOGY OF PAINTS 


altered. The old-time painter when he condemned a 
mixed paint would smell it, taste it, rub it between his 
thumb and forefinger, smell it again, look wise, and say 
despairingly, “fish oil.”’” As a matter of fact, the adul- 
teration of paints was seldom, if ever, caused by the 
addition of fish oil, for the reason that the price of a 
good fish oil always approximated that of a raw linseed 
oil, and there were so many other cheaper paraffin oils 
to be had that the occurrence of fish oil in a mixed 
paint was relatively rare. The specific gravities of fish 
oils freshly made and containing no admixture of other 
species, but representing the pressing of only one species, 
are aS a general rule below .g27. Its iodine number is 
so close to that of linseed oil that in its raw state, except- 
ing for its characteristic odor and the Maumene test, it 
is rather difficult to differentiate these oils with cer- 
tainty. The author is inclined to believe that this 
characteristic odor is due to phosphorous decomposition 
compounds. If a linseed oil be heated to 500° F., mixed 
with Japanners Prussian brown or Prussian blue, it de- | 
velops acrolein, which is identical in odor with that from 
the fish oil. When Menhaden oil is treated with 8 ounces 
of litharge to the gallon and kept at a temperature of 400° 
to 500° F., for ten hours, it thickens perceptibly and can 
be reduced proportionately with naphtha, but the amount 
of loss by this treatment with litharge makes it very 
expensive in the end. 

The results obtained from the proper grades of fish 
oil warrant the use of fish oil in the hands of an intelli- 
gent manufacturer, and if used up to 75 per cent pro- 
duces excellent results for exterior purposes. For interior 
purposes fish oil does not seem to be desirable, for it 
gives off noxious gases for a long time. When fish oil 
is mixed with linseed oil even up to 75 per cent it 


FISH OIL 239 


gives excellent and lasting results and does not show 
any hygroscopic properties, but when used in the raw 
state, particularly in conjunction with pigments which in 
themselves are not catalytic driers, the results are not 
satisfactory. 

For some years some of the enamel leather and print- 
ing ink manufacturers have adopted the use of fish oil 
as a medium to replace linseed oil with excellent results, 
and the enamel leather which is produced, while not so 
high in gloss as that made entirely of linseed oil, is much 
more flexible and possesses an unctuousness which pre- 
vents it from cracking. But fish oil for leather purposes 
shows a peculiar defect, and a campaign of education 
will be necessary if ever this material is to be used for 
the manufacture of shoes or auto tops, for fish oil, par- 
ticularly when it originally has a high acid number, seems 
to effloresce and give an undesirable bloom to enamel 
leather, which, however, can be removed from the sur- 
face by the ordinary application of either benzine or a 
mixture of benzine and turpentine. At the same time, 
enamel leather is very largely used for carriage and 
automobile tops, and for shoes, and wherever it is used 
for these purposes these products are continually polished. 

Menhaden oil is the only oil, with the possible excep- 
tion of China wood oil, which can be used for making 
‘ smoke-stack paints that will withstand the action of 
excessive heat and light. When treated as described, its 
intrinsic value is far beyond that of linseed oil, and a 
smoke-stack paint made in this manner sells for one-third 
more than a linseed oil paint. It is impossible, however, 
to treat Menhaden oil for this purpose, except at an 
excessive cost, because the acrolein developed nauseates 
the workmen, the loss in evaporation is very large, and 
the treatment with litharge is such that the oil must 


240 CHEMISTRY AND TECHNOLOGY OF PAINTS 


be thinned before it has an opportunity to compound or 
semi-solidify. In its raw state, after treatment with 
animal charcoal and infusorial earth, it is used to ‘some 
extent with a heavy boiled linseed oil for making water- 
proof roof paints, for painting canvas, freight cars, ship 
decks, etc. When mixed with linseed oil up to about 
25 per cent it is extremely difficult to determine the 
amount present by means of its chemical constants or 
characteristics. 
The following are the constants of the Menhaden oil 

which is generally used in the United States for making ~ 
heat-resisting paints: 


CONSTANTS OF FISH OIL 


Specific Gravity a5 acne eee 0.931 
paponificationns © a. ee ear ae QO. 
lodine Value ..7 ues 4c ee 150-165 


There is a great demand for baking japans which 
shall be flexible and at the same time be so thoroughly 
baked that they adhere to the surface most tenaciously 
and form an excellent enamel, and for this purpose we 
know that the reasonable use of fish oil improves baking 
japans very much indeed. 

We are also aware that along the seacoast, where 
paint disintegrates very rapidly on account of the sea 
air, a fairly liberal use of properly treated fish oil serves 
a useful purpose. 

When red lead is mixed 33 lbs. to a gallon of linseed 
oil it thickens up after a very short time and becomes 
unfit for use. A properly neutralized fish oil prevents 
the hardening or setting of the red lead in the package, 
and a paste of this material can be transported a great 
distance and will last many months in a fresh and soft 
condition. 


FISH OLL 241 


In the tests made by the author on fish oils and tin- 
seed oil without the admixture of driers, it was found that 
the Menhaden fish oil and the linseed oil dried approxi- 
mately the same, but the seal oil and whale oil were 
still sticky after two weeks. This may be an unfair 
test, for these other oils can be manipulated with the 
proper driers and they will serve a fairly good purpose, 
but inasmuch as Menhaden fish oil appears to be satis- 
factory for this test even without a drier its superiority 
over the animal oils is apparent. 

Menhaden oil should, of course, be used with a drier, 
and for that purpose the best results are obtained by 
means of a tungate drier. A tungate drier is one in 
which tung oil or China wood oil is boiled with a lead 
and manganese oxid, and when the solution is complete 
this is then mixed with a properly made resinate of 
lead and manganese. Such a drier becomes soluble in 
the oil at temperatures over 100° C., and hardens the 
resulting paint very thoroughly. For fabrics, however, 
fish oil must be heated to a temperature of over 200° C., 
and if air is injected at such a temperature the glycerides 
are expelled and thick oil is produced which, in con- 
junction with the drier just named, is equally good for 
printing inks. It is advisable, however, to add at least 
25 per cent of either a heavy bodied linseed oil or a raw 
‘linseed oil which does not “break”’ before the manipula- 
tion just referred to is begun. 

For stacks, boiler fronts, etc., the treatment of fish 
oil up to 220° C., with litharge makes a heat-resisting 
medium that is far superior to anything excepting China 
wood oil, and for both heat-resisting and exposure to the 
elements fish oil is superior to China wood oil. 

The following is taken from the U. S. Navy Depart- 
ment specifications for fish oil for paint purposes: 


242 CHEMISTRY AND TECHNOLOGY OF PAINTS 


Quality 
1. To be strictly pure winter-strained, bleached, air-blown Men- 
haden fish oil, free from adulteration of any kind. 


Chemical Constants 
2. The oil shall show upon examination: 


Maximum Minimum 


Specie STAVILY sce eo eee 0:935 6.030 
Iodine number (Hanus)....... 165 145 
Acid number sav. aene eee TE 


Physical Characteristics 

3. The oil when poured on a glass plate and allowed to drain 
and dry in a vertical position, guarded from dust and exposure to 
weather, shall be practically free from tack in less than 75 hours at 
a temperature of 70° F. When chilled, the oil shall flow at temper- 
atures as low as 32° F. 


Among the best fish oils is the sardine oil of the north- 
west coast of the United States which has an iodine number 
as high as 175. 

When this oil is heated in a glass vessel with 10 per cent 
kerosene or an equally slow drying petroleum distillate a 
large part of the odor of the oil appears to be carried off. 

Sardine oil to which 25 per cent of China wood oil 
varnish has been added has given excellent results as a 
smokestack paint and the same may be said of the addition 
of perilla oil to sardine oil, but in each case and for hot 
stacks 3 per cent of a good liquid drier should be added. 

The northwest oil is similar in all its characteristics 
to the Japanese herring oil described in the foilowing 
chapter. 


CHAPTER eX VIL 
MISCELLANEOUS OILS 


HERRING OIL! 


WITHIN recent years the subject of fish oils has 
received considerable attention, first from the leather and 
soap manufacturers and subsequently from the paint 
chemist. Hitherto fish oil played the réle of a rather un- 
important by-product in the course of fertilizer or ‘‘scrap”’ 
production, for which there seems to have been always 
a large demand. 

As the peculiar properties and industrial possibili- 
ties of fish oils became more thoroughly appreciated in 
the light of investigations carried out by progressive 
manufacturers, the fish oil industry received a new 
lease of life and grew until it rivalled in, importance 
the fertilizer industry to which it had previously been 
tributary. 

Of the numerous varieties of fish oils which have 
at one time or another appeared upon the market, Men- 
haden oil alone seems to have established itself on a firm 
basis in the manufacture of special kinds of heat-resisting 
paints. Its application, therefore, is no longer an experi- 
ment; it is an established fact. : 

Latterly, attention has been more particularly directed 
toward seal, whale, cod, porpoise, and herring oils, with 


1 By A. Lusskin, 8th Int. Congress of Applied Chemistry; written 
in the research laboratory of Toch Brothers under the direction of 
the author. 

243 


244 CHEMISTRY AND TECHNOLOGY OF PAINTS 


a view to investigating their utilizability in the indus- 
tries. Of these, seal, cod and porpoise body oils have 
proved to be in many ways as good as Menhaden oil, 
but are beyond the reach of the paint manufacturer on 
account of considerations of price. 

Whale oil, which is now obtainable in the form of a 
clear, pale material, comparatively free from objection- 
able odors, has not as yet been successfully manipulated 
to give very good drying results. 

In the treatment of fish oils, several considerations 
must be constantly kept in mind in order to obtain the 
best results: 

1. The oil must be free from high melting point 
glycerides or fatty acids; or, to use the technical term, 
the oil must be “‘winter-pressed.”’ Most fish oils contain 
a large amount of saturated glycerides of the nature of 
palmitin which separate from the oils on standing for 
any length of time at a low temperature. When these 
have been removed from the oil, the resulting product is 
found to be much more amenable to successful treatment 
than it otherwise is. It would seem that these high 
melt ng point fats tend to retard or to prevent the drying 
of fish oils, giving films which remain greasy for a very 
long time. | 

2. Very frequently, oils are received which have a 
high content of free fatty acids. In the case of one 
sample of herring oil, this was as high as 41.9. Under 
such circumstances, it is perfectly evident that the drying 
of the oil would be very largely inhibited. In addition, 
such an oil, used as a paint vehicle, in conjunction with 
pigments like red lead, white lead, and zinc oxid will, 
in a very short space of time, “liver” up and form the 
lead and zinc soaps of the fatty acids. This was very 
largely responsible for the poor results obtained with the 


HERRING OIL 245 


fish oils which were first introduced on the market. 
The free fatty acids are formed when the oil, extracted 
from the fish by boiling in water, is subjected to the 
action of the decomposition products from the bodies of 
the fish for a longer time than is absolutely necessary 
to break open the oil-containing cells. 

3. Finally it must be remembered that driers, which 
serve very well for vegetable drying oils, will not, in 
general, function properly, when utilized for fish oils. 
The tungate driers, and particularly the cobalt tungates, 
can generally be depended upon in the case of oils which 
do not yield to the action of the ordinary linseed oil 
driers, provided however, the two conditions named above 
have been satisfied. 

The writer recently had his attention called to several 
grades of herring oil, which, at first glance, appeared 
desirable from the paint manufacturer’s standpoint. 
Accordingly an investigation was started to test its 
adaptability for paint purposes, and to compare its be- 
havior with that of Menhaden oil. | 

Herring oil occurs in the bodies of Clupeus C. and 
V. (Japanese herring varieties) and Clupeus harengus 
(European or North Sea herring). 

The method of extracting the oil from herring is the 
one universally used in the fish oil industry, viz., ex- 
.traction in boiling water. 2 

Two representative samples of herring oil, furnished 
by two of the leading oil concerns in the States, were 
experimented with in conjunction with Menhaden and 
other fish oils. The following analytical constants were 
obtained: 





























246 CHEMISTRY AND TECHNOLOGY OF PAINTS 
No. Color Odor Sp. Gr. | Acid | Iodine 
15°C | Value| Value 
#1 Herring Oil Very Pale Good 0:0240)| 2254 aie 7e0 
#2 Herring Oil Dark Brown Bad 0.0210 P4r, Quai ore 
Blown Oil #2 Deep Red | Almost | 0.9654| 25.7) 89.94 
None 

Winter-Pressed dL Extremely Fair O.920:.| 30.4, -140.8 
#i Crude Whale Oil | Very Pale Good, «| 0.92307] ©20)} 430.5 
#1 Filt. Whale Oil | Very Pale Good ©. | 0.020395 223i 7eec 
#2 Filt. Whale Oil | Pale Amber | Very good | 0.9222 | 14.5 | 142.9 
Porpoise Body Oil Very Pale | Very good | 0.9268] 2.8 | 132.3 
Menhaden Oils 
Ext. Bleached 

Winter Oil Very Pale Fair 0.0272) O7ns et somd 
Bleached-Refined Pale Amber | Not bad | 0.936345) 57g pom 
Regular Deep Red Bad 0.9284 | 8.4) 165.7 











* The part of the table below the asterisk (with exception of the 
acid values), is from a paper on Fish Oils delivered by M. Toch 
before the Amer. Chem. Soc., Dec. 1911, and published in the Journal 
of Industrial and Engineering Chemistry. 


Crude herring oil, even though very dark in color, 
yields a very clear, pale product when treated with 
Fuller’s earth for a short time at about 250° F., and then 
for some time longer, at the temperature of boiling 
water. In addition the odor is considerably improved. 

In the case of the crude herring oil listed above, the 
sample was kept for several hours at about 60° F. to 
permit high-melting fats to separate out. The portion 
which remained liquid corresponded to a winter-pressed 
oil. Since the acid and iodine numbers were prac- 
tically unchanged it seems that the solid fats contained 
saturated and unsaturated compounds in about the same 
proportions as the crude oil. 


CORN OIL 247 


Another sample of the oil was heated to 320° F. and 
blown with air for about 8 hours. The effects produced 
on the constants are shown above. The oil was very 
heavy and viscous but had the deep red color which fish 
oils so readily assume. It must be noted also that the 
“fish”? odor was very faint. The reduction in acid value 
would seem to indicate that the oil contained fatty acids 
which were volatile at the temperature of blowing. 

Attempts to dry the samples of herring oil did not 
prove successful, even when very powerful driers were 
used. This cannot, however, be interpreted to mean 
that herring oils are, in general, not- capable of drying. 

Porpoise body oil and Menhaden oil, under similar 
conditions, dried satisfactorily. 

The blown herring oil could very well be used for the 
production of smoke-stack paints and for paints intended 
to resist the ‘“‘chalking”’ action of salt air. Herring oil 
is at present used to a certain extent in leather manu- 
facture together with some of the other fish oils like 
Menhaden and whale oil. In regard to herring oil, as 
with many of the other materials which are being intro- 
duced from time to time, the final word cannot be spoken 
until many more specimens have been examined and 
given a fair test. 


CorN OIL 


Corn oil is made in very large quantities in the 
United States, and is of considerable value as a paint 
material. It is seldom so much cheaper than linseed oil 
or China wood oil that it is used as an adulterant for 
these oils; in fact, many manufacturers would probably 
use it irrespective of the price up to about to per cent 
in certain classes of mixed paints in order to prevent 
hardening or settling. A large number of paint manu- 


248 CHEMISTRY AND TECHNOLOGY OF PAINTS 


facturers in the United States who grind heavy paste 
paints, such as Venetian reds, ochres and white paints 
containing large amounts of barytes, frequently use from 
Io to 70 per cent of corn oil, not because it is any 
cheaper than linseed oil, but for the reason that the 
resulting mass never becomes hard in the package as it 
‘does where pure linseed oil is used. 

Corn oil has a great analogy to soya bean oil, with the 
one exception that corn oil is not as pale nor can it be 
bleached as pale as soya bean oil, and when it is bleached 
by chemical means it dries very badly. 

Corn oil is known in England as maize oil. Paint 
manufacturers in England appear to have very little 
knowledge of this oil and regard it as a non-drying oil, 
and yet corn oil is even more than a semi-drying oil, 
particularly when heated with strong drying oils like 
China wood oil and cobalt and manganese drier. In 
the textile arts, such as the manufacture of linoleum and 
table oilcloth, where flexibility is desired, large quantities 
of corn oil are from time to time used with excellent 
results. When an oil like corn oil is used for paint 
purposes in limited quantities its characteristic of slow 
drying or tacky drying is eliminated if it is properly ma- 
nipulated. Corn oil will take up the lead and manganese 
salts just the same as linseed, but in conjunction with 
linseed oil. It can be blown and can be thickened by 
heat, and being very flexible it has a distinct advantage. 
It has been stated, although the author has not tried this, 
that for priming new wood half corn oil and half linseed 
oil with sufficient drier and volatile solvent produce a 
priming coat to which a second coat of linseed oil paint 
will adhere perfectly. 

The physical and chemical constants of corn oil 
cannot be given exactly for the reason that samples vary. 


CORN OIL 249 


Its specific gravity will run from 0.920 to 0.926; its 
saponification value will average 190; and its iodine 
value will average 120, although several samples exam- 
ined by the author have shown as high an iodine value 
aS 130. 


CHAPTER XVIII 
TURPENTINE 


TURPENTINE occupies the same relative position among 
the vehicles of paints and varnishes as white lead does 
among the pigments. It is impossible to say for how 
many generations turpentine was the only solvent or 
diluent known to the paint and varnish industry, and 
therefore when other solvents were introduced they were 
looked upon as adulterants. 

The methods used in the manufacture of turpentine 
are very well known; the sap of the Georgia pine and 
two or three other species of pine trees growing in 
the southern part of the United States is collected 
and distilled with steam. The distillate is known as 
turpentine, and that which remains behind in the still 
is known as rosin (colophony). American turpentine 
has a very pleasant odor, and from several combus- 
tion analyses made by the author, the composition 
of turpentine taken directly from the barrel as shipped 
from the South corresponds absolutely with the theo- 
retical formula CiHis. It has absolutely none of the 
qualities of a paint preservative, but is used only to 
increase the spreading power and working quality of 
paint. Entirely too much stress is laid upon the value of 
turpentine as a paint vehicle, and the sooner the chem- 
ist and the consumer realize that turpentine is simply 
an auxiliary, the sooner will better substitutes be used. 

If the forestry department of this government will not 
interfere with the destruction of the trees, turpentine will 
become a chemical curiosity within the lifetime of many 
of us, unless new trees are planted. 


250 


TURPENTINE 251 


-American differs from Russian turpentine in odor and 
in specific gravity, although in chemical composition they 
are alike. The specific gravity of American turpentine 
is about .865 when fresh, but it will rise as high as .90 
when old. It is supposed to boil at 350° F., but that also 
depends very largely on the condition of the turpentine 
and whether it has been exposed to the air. Turpentine 
flashes according to the text-books, and according to the 
majority of specifications that are written, at 105° F. 
As a matter of fact, its flash point is 98° F. Turpentine 
evaporates very slowly, and on account of this slow 
evaporation it is very highly prized as a varnish diluent, 
but there are paraffin products that have lately been 
invented that evaporate just as slowly and leave no resi- 
due behind. Pure turpentine when poured on a sheet 
of filter paper should leave absolutely no residue behind, 
and a drop of water poured on the paper after the tur- 
pentine has evaporated must be absorbed as readily by 
the paper as before it was immersed. In this regard the 
petroleum naphtha solvents are identical. They will be 
described in the proper chapter. 

The following organic analyses of French, American, 
and wood turpentines show that French turpentine and 
American turpentine are both represented by the for- 
mula C,oHis, the American turpentine being practically 
‘ 100 per cent pure. Wood turpentine, however, may be 
shown to be 97.7 pure, the 25 per cent of impurities con- 
sisting of pyridene bases, formalin, and other wood 
decomposition products. Since these investigations were 
made in 1905, samples of wood turpentine have been 
placed on the market which are so nearly identical with 
the sap turpentine that it is almost impossible to dis- 
tinguish them, only an experienced consumer being able 
to tell the difference, the wood turpentine having a pe- 


252 CHEMISTRY AND TECHNOLOGY OF PAINTS 


culiar odor which is lacking in the sap turpentine.- No 
matter how thoroughly a wood turpentine is purified, 
there is always a smell of sawdust which clings to it and 
which can be recognized by a person once familiar with 
the odor. These pure grades of wood turpentine cannot 
be said to be adulterants of the sap turpentine. 


FRENCH TURPENTINE 


First Analysis Second Analysis 





Weight of sample............0.2040 grams. 0.1870 grams. 

GOs obtained sr jeer 0.6558 grams. 0.6009 grams. 

HO obtained va. sae ©. 2161 grams. 0.1980 grams. 

| Hence, percentage composition, 

Carpon kine ot oe ee 87.67 per cent. 87.63 per cent. 

Hydrogen.) 25 328 eee 11.87 per cent: 11.87 per cent. 
‘Potalinoe eos reer 99.54 per cent. 99.50 per cent. 


AMERICAN TURPENTINE 


First Analysts Second Analysts 








Weight of samples... .2 s..20n17 77 erm, 0.1828 grams. 

CQ. ‘obtainediae am eee 0.5714 grams. 0.5878 grams. 

HO obtained. we eee ©.1923 grams. 0.1968 grams. 
Hence, percentage composition, 

Carbon 4a. See eee 87.70 per cent. 87.69 per cent. 

Hydrogen sie eee 12 -12*per cent: 12.07 per cent. 
Total idee oe 99.82 per cent. 99.76 per cent. 


Woop TURPENTINE 


First Analysis 





Second Analysts 


Weight of samplé......) 20,100 eramns. 0.1656 grams. 

COs; obtained 365; sence es 0.5939 grams. 0.5202 grams. 

HO obtained 4: = omen ee ©. 2042 grams. 0.1785 grams. 
Hence, percentage composition, 

Carbon. tigen tomer eee ee 85.65 per cent. 85.67 per cent. 

Hydrogen, 3. a eee 12.10 per cent. 12.08 per cent. 

Oxygen. a ee 2 eee cents 2.25 per cent. 
Dotal act, ae seeee 100,00 per cent. 100.00 per cent. 


TURPENTINE 253 


In the Journal of the American Chemical Society ! 
for 1904 a very exhaustive treatise is given on spirits of 
turpentine, in which it is demonstrated that the only 
reliable chemical test for differentiating between’ wood 
turpentine and the old spirits is the determination of the 
iodine absorption number. But even this is now growing 
to be very unreliable, for the reason that so much care 
and skill is exercised in the manufacture of wood tur- 
pentine that it is almost impossible to distinguish it 
from the sap turpentine. A great deal has been written on 
the optical activity of turpentine when observed through 
the polariscope. The paint chemist, however, cannot 
point with any degree of certainty to this test, excepting 
where a coarse mixture of benzine, rosin oil, etc., is made, 
and up to the present writing very highly refined tur- 
pentine and sap turpentines show little or no difference. 
The admixture of rosin oil, benzine, benzene, kerosene, 
and adulterants of that kind are, of course, differentiated 
with more or less ease. 

Turpentine is by no means used as largely as it was 
prior to 1906. The reason for this, strange to say, is a 
moral one and not a physical one. Ten years ago it 
would have been thought impossible to do without spirits 
of turpentine in paint or varnish. Today it is used by 
many people who think they have to use it, and by others 
‘who use it in high grade piano and other finishing varnishes, 
because they believe it gives a physical flow to the varnish 
which cannot be obtained by the use of anything else. 
This, however, is disputed by many manufacturers. At 
any rate, the fact remains that several years ago turpentine 
rose from a price of about 40 cents per gallon to $1.13, 
for a number of men in the southern part of the United 
States attempted to corner the market. Before, how- 

1 “ Analysis of Turpentine,” by Jno. M. McCandless, p. 981, 1904. 


254 CHEMISTRY AND TECHNOLOGY OF PAINTS 


ever, the price reached the abnormal figure of $1.13 some 
of the officials of the United States Navy made exhaust- 
ive experiments and showed that the turpentine sub- 
stitutes of the petroleum type were absolutely as good 
and served the same purpose as spirits of turpentine. 
Not to go into the details of this, about five years ago 
the United States Navy substituted some 70,000 gallons 
of turpentine by turpentine substitute, and the resulting 
paint gave just as good service and the saving in price 
was very great. The men who had attempted to corner 
the market and enrich themselves at the expense of others 
were finally ruined, and the whole turpentine industry 
received a staggering blow, from which at this date it 
has not entirely recovered. The price dropped until it 
hovered around 4o and 50 cents, but in the meantime 
the paint industry had learned the lesson, which was of 
tremendous value, that it could do without turpentine 
entirely. 


TURPENTINE ! 


Distillation of Pure Gum Spirits of Turpentine 
Will not begin distilling lower than 153° C. 
t. to 2% distills over by 153° C. 


50% 66 66 66 I57- Ge 
80% Ts 6c 6c Tos re 
85% és ST STOCm es 
95% 6c ‘< qs 165.5° oO 
Sometimes 

50% 6“ 6“ 66 159° CX 
80% a (Coe TOO Rae 
85% ts £6 SC 65 


95% should be distilled by 165.5° C. 


* Data from J. E. Teeple, New York City. 


TURPENTINE 255 


Distillation of Steam Distilled 
Wood Turpentine 


Usually begins distilling at about 





0535.0, 

50% distills over by (eo eh Or 
eae TOA se, 
85% . Bee tones C, 
95 % “ce ce ope CG. 
Sometimes 
80% CT: 6 6c 163° CG 
85% (79 ce (73 164° C. 
90 % cc ¢ ce LOG-RS Cs 

a9 (79 c¢ O° = a 
95% ate - No. tor. Section of the long leaf turpen- 


This latter would be con- 
sidered a very good grade. 
Sometimes only 60% to 70 % will distill by 165.5° C.— Poor grade. 


tine pine — Photomicrograph X310. 


Woop TURPENTINE 


The turpentine in the United States is held in such 
strong hands that the price is abnormally high, and within 
the last five years pine, sawdust, shavings, tree stumps, 
and old logs have been placed in retorts and distilled 
in the same manner as the sap of the pine tree. A liquid 
is obtained which is sold under the name of wood tur- 
pentine and is guaranteed by many to be absolutely the 
same material as that obtained from the sap of the 
tree. It must be frankly admitted that there are some 
wood turpentines on the market at this writing which 
are so similar to the real article that it is almost impos- 
sible to differentiate between them. And yet there is 
always a peculiar distinctive odor to these wood _tur- 
pentines which does not exist in the pure turpentines. 
Several organic analyses of this variety of wood tur- 
pentine by the author have shown that the formula 
is not CioHi., but that it is a most complex mixture con- 
taining more than a trace of pyridene bases, formic acid, 


256 CHEMISTRY AND TECHNOLOGY OF PAINTS 


formaldehyde, and other products from the destructive 
distillation of wood. But wood turpentine is being 
improved so continually that these impurities are being 
largely removed. For exterior painting, wood turpen- 
tine that contains only a trace of these impurities is 





No. to2. Cross AND LONGITUDINAL SECTIONS OF WHITE PINE— 
Photomicrograph X180. 


just as good as the sap turpentine, and for indoor paint- 
ing it is no better than a number of the petroleum 
products and costs very much more money. It cannot 
be said that it has advantages in exterior painting .over 
the benzine products. One reason why it can be used on 
exterior work and not on interior work is that the dis- 
agreeable odor it sometimes gives off becomes obnoxious 
to those who use it on interior work. The pure grades 


TURPENTINE 257 


of wood turpentine cost within 5 cents per gallon of the 
price of sap turpentine, and judging from the large 
number of concerns that have sprung up within the last 
five years for the manufacture of wood turpentine and 
then slowly disappeared, it is reasonable to infer that the 
industry is not profitable. 


PHYSICAL CONSTANTS OF TURPENTINE, TAKEN FROM 
BeeCAPICATIONS OF THE U.-S.. NAVY DEPT., 1923, 
AND THOSE OF THE AMERICAN SOCIETY 
FOR TESTING MATERIALS, 1924 


Maximum Minimum 
Sreeoabdavity, 15.s/T5 Cl.) ok. 10, 875 0. 862 
Refractive Index at 20° C. 
STEEL SSF Bch ae ee 1.478 1.468 
NV ROOCIMPSTEDCTN GING seh reir cea Pk oe en. 1.478 1.465 
Residue after polymerization with 
28 NHe SO,: 
Gum spirits — 
Poitier percelts se .  e, as. eS 2 Omsene te a ieeeze 
emicuvemndex-at 20° Con)... 205s. ee. I.500 
Wood turpentine — 
PD rPMeE OCI CCl Ur ia Leas. ante ot we BCR toes 
feetracuve Index at 20%.C...; Js 2. 2 1.48 
Initial boiling point at 760 mm. pressure. 1.60°C. 150°C. 
Distilling below 170° at 760 mm. pressure, 
| Nie BUSLat 10 Oe a gpa geeanh ee aes Bo ONC Ter WE try aaa? go 


For detailed methods of testing and analysis of turpentine the 
reader is referred to both of the above specifications. 


CHAPTER] XLX 


PINE OIL! 


ONE of the industries which has developed as a result 
of the policy of conservation in the United States is the 
manufacture of useful products from resinous woods. 
Enormous quantities of the latter, which in previous 
years were considered of little or no use and were deliber- 
ately burned in huge burners especially constructed for 
the purpose, or which were simply allowed to go to waste, 
are now being economically and profitably manipulated 
for the recovery of turpentine, pine oil, and rosin, or the 
production of tar oils, pine pitch, and charcoal. 

The two commercially important methods in vogue 
are, first, the steam and solvent or extraction process, and 
second, the destructive distillation process. 

H. T. Yaryan? has taken out letters patent on a 
process for extracting turpentine and rosin from resinous 
woods, which very well illustrates the extraction method 
as practised today. Resinous wood, reduced to fine 
chips by passing through a wood chipper, is charged into 
an iron vessel through a charging door at the top. The 
wood rests upon a false bottom over a coil supplied with 
superheated steam for producing and maintaining the 

1 Journal of Society of Chemical Industry, June 15, 1914, No. II, Vol. 


xxxill, by Maximilian Toch. 
2 The following is a list of the Yaryan U. S. Patents: 


No. 915,400, March 16, 1909 934,257, september 14, 1909 
915,401, March 16, 1909 964,728, July 19, I9gI10 
915,402, March 16, 1909 ~ 992,325, May 16, 1911 


922,369, May 18, 1909 
258 


PINE OIL 250 


proper temperature within the iron chamber. The door 
at the top and the discharge door at the bottom are 
closed, and the current of superheated steam is driven 
into the mass of chips. This is continued until the more 
volatile turpentine has been vaporized and driven over 
into the condensers. The wood in the extraction vessel 
is left charged with a small percentage of heavy turpen- 
tine, together with pine oil and rosin. Steam is shut off, 
the excess moisture in the hot wood is removed by 
connecting the vessel with a vacuum pump, and finally 
a liquid hydrocarbon (boiling point, 240°-270° F.) is 
sprayed over the top and allowed to percolate down 
through the pores of the wood. The resinous materials 
are thus thoroughly and completely extracted, and passed 
into a storage tank, from which they are pumped into a 
still used for separating the component parts of the solu- 
tion. From the still the hydrocarbon solvent is readily 
separated from the heavier pine oils by distillation under 
reduced pressure, on account of the great difference in 
the boiling point between the pine oils and the hydro- 
carbon solvent, the former boiling between 350° and 370° F. 
The pine oils are in turn separated from the rosin by 
distillation with superheated steam. 

Other so-called “low temperature” processes deserve 
mention as possessing features of merit, although sufficient 
data does not appear to be available to show their true 
value when operated on a large commercial scale. The 
Hough process, for example, is to be considered essentially 
a preliminary treatment in the manufacture of paper 
pulp from resinous woods. Chipped wood is placed in a 
retort and subjected to the action of a dilute alkali. The 
rosins are saponified and the soap separated from the 
alkaline liquor by cooling and increasing the alkali con- 
centration to the desired degree. The rosin soap may be 


260 CHEMISTRY AND TECHNOLOGY OF PAINTS 


sold as such, or treated with acids for recovery of the 
rosin. The turpentine and pine oils are recovered either 
by preliminary treatment with steam or during the early 
stages of the cooking process. 

It will be noted that in the low temperature processes 
the only products recovered are turpentine, pine oils, 
and rosins, the first two removed by the action of steam, 
either saturated or superheated, and the latter by extrac- 
tion by use of a neutral volatile solvent or a saponifying 
agent. The so-called “spent wood” may be used either 
for the manufacture of paper pulp or as a fuel to generate 
the power necessary to carry out the process. 

In the destructive distillation process, the wood, in the 
form of cordwood 4 ft. to 6 ft. in length and 4 in. to 8 in. 
in diameter, is placed in a horizontal retort and the tem- 
perature gradually raised until the wood is thoroughly 
carbonized. The factor of greatest importance in the 
successful operation of this process is temperature control, 
as it is essential that the turpentines and pine oils be 
removed in so far as is possible before the temperature at 
which the rosins and wood fibre begin to decompose is 
reached. The total volume of distillate, as well as the 
percentage volume of each of the several fractions thereof, 
is largely dependent on the degree of temperature control. 

Destructive distillation of resinous wood was first 
carried out in earthen trenches, the combustion being 
controlled by partially covering the wood with earth. 
Tar and charcoal were the only products recovered. 
Then came the beehive oven, operated in much the same 
crude manner, but recovering the more volatile distillates, 
in addition to tar and charcoal. This was in turn super- 
seded by the horizontal retort, externally heated, hot 
gases being circulated either through an outer shell or 
through pipes within the retort. Next came the bath 


PINE OIL 26f 


process, wherein the cordwood was immersed in a bath of 
hot pitch or rosin, thereby volatilizing the turpentine and 
lighter pine oils and dissolving the heavier oils and rosins. 
After this preliminary treatment the bath was withdrawn 
and the wood subjected to straight destructive distillation. 

More recently! a retort has been devised utilizing the 
basic principle of the laboratory oil bath. The retort is 
heated by means of a layer of hot petroleum oil which is 
kept continually circulating between the retorts and an 
outer cylindrical shell that completely surrounds the re- 
tort proper. In this way it is claimed that the tempera- 
ture of distillation can be accurately controlled. The 
turpentine and pine oil obtained are fractionated and 
rectified by subsequent steam distillation. In running the 
retort the temperature of the oil bath is so regulated that 
the heat inside does not exceed 450° F. before all the 
turpentine and pine oil have been distilled. 

The products of destructive distillation by the several 
processes are in each case of very much the same general 
nature, namely, turpentine, pine oils, tar oils, pine tar, 
pitch, and charcoal. In some instances low-grade rosin 
oils are also produced. 

“Light wood” does not refer to woody fibre which 
has a low specific gravity. The name originated from 
the fact that this particular wood is so rich in oil and 
resinous material that it is readily used for lighting fires. 
In the southern portion of the United States little bundles 
of “light wood” are for sale in strips about % inch in 
diameter and 1 foot long. When a flame is applied to 
one of these strips of wood it becomes useful for lighting 
fires, hence the name “light wood.’ The author has seen 
“light wood” so rich in resins and oily material that by 
transmitted light a thin section looked like translucent 

1 T. W. Pritchard, Journal of Society of Chemical Industry, 1912, 31, 418. 


262 CHEMISTRY AND TECHNOLOGY OF PAINTS 


ruby glass. It is this particular wood which is most 
used for the distillation of wood turpentine, pine oil, and 
rosin. 

The product from that type of pine tree from which 
turpentine is obtained has always been regarded as pro- 
ducing two materials when the sap has been collected and 
distilled. The one material is turpentine, and the other 
rosin. About ten years ago, when destructive and steam 
distillation of pine wood became a practical industry, a third 
substance was recovered. ‘This material, intermediate be- 
tween turpentine and rosin, is now known as “pine oil.” 

As far as the author knows, no one has yet determined 
the chemical constitution of this intermediate product of 
the pine tree, which has been designated as ‘‘pine oil.” 
Two years ago the writer started this investigation, which 
is practically finished. There is as yet no standard of 
purity for pine oil, but that it has a definite chemical 
composition is now fairly well established. The only 
original investigation of the chemical composition of pine 
oil was carried out by Dr. J. E. Teeple! on long leat 
pine oil. 

Dr. Teeple says: ‘‘The commercial long leaf oil, as 
it comes on the market, is either clear and water white, 
containing 3 or 4 per cent of dissolved water, or it may 
have a very faint yellow color and be free from dissolved 
water. The specific gravity ranges from 0.935 to 0.947, 
depending on freedom from lower boiling terpenes. A 
good commercial product will begin distilling at about 
206° to 210°, and 75 per cent of it will distill between the 
limits 211°-218° and 50 per cent of it between 213°-217°. 
A sample having a density of 0.945 at 15.5° showed a 
specific rotation of about [a] =* — 11°, and an index of 


1 Journal of American Chemical Society, 1908, 30, 412; Journal of Society 
of Chemical Industry, 1908, 346. 


PINE OIL 263 


refraction of Np 1.4830. In fractional distillation of the 
oil the specific gravity of the various distillates rises 
regularly with increasing temperature, becoming steady 
at about 0.947 at 217°. 

“Tf the oil consists essentially of terpineol, C,H,30, 
it should be easy to convert it into terpin hydrate, 
CyoH2oO2 + H.O, by the method of Tiemann and Schmidt. 
The conversion was found to proceed easily when the oil 
was treated with 5 per cent sulphuric acid, either with 
or without admixture with benzine. If agitated contin- 
uously, the reaction is complete within 3 or 4 days. If, 
on the other hand, the mixture is allowed to stand 
quietly, the formation of terpin hydrate extends over 
several months and produces most beautiful large crystals, 
which, without recrystallizing, melt at 117°-118°. When 
recrystallized from ethyl acetate they melt at 118°. The 
yield is about 60 per cent of the theoretical. This 
forms such a simple, cheap, and convenient method of 
making terpin hydrate that it will doubtless supersede 
the usual manufacture from turpentine, alcohol, and 
nitric acid, and instead of terpin hydrate serving as raw 
material for the manufacture of terpineol, as heretofore, 
the reverse will be the case.”’ 

The term “pine oil,” as now understood, is the heavy 
oil obtained from the fractionation of crude steam dis- 
tilled wood turpentine. When the sap of the pine tree 
is subjected to distillation in a current of steam the 
volatile liquid — turpentine — consists almost entirely of 
the hydrocarbon, pinene (CioHis). When, however, the 
trunk, stumps, and roots of the same tree have been 
allowed to remain on the ground for a number of years 
and are then steam distilled, there are obtained, in addition 
to the turpentine and rosin, certain heavier oils formed 

E Ber, 720; 171. 


264 CHEMISTRY AND TECHNOLOGY OF PAINTS 


by hydrolysis and oxidation as a result of exposure to the 
atmosphere. To the heavier oils thus formed and yielded 
up in the process of steam distillation the term “pine oil”’ 
is properly applied. 

Pure pine oil has a very pleasant aromatic odor, similar 
at times to the oil of caraway seed or the oil of juniper 
seed. When pine oil is impure it is very difficult to use it 
for interior work on account of its pernicious odor of 
empyreumatic compounds. It has been used to a con- 
siderable extent for making paints which should dry 
without a gloss, and as a “‘flatting’’ material it has been 
very successful. It has the excellent cuality of flowing 
out well under the brush and of not showing brush marks, 
the latter because it evaporates so very slowly. It is 
a very powerful solvent, and many of the acid resins 
which have a tendency to separate when they are in- 
sufficiently heated with drying oils will remain together 
when pine oil is added. Pine oil can be used to a con- 
siderable extent as a diluent in nitrocellulose solutions, 
and as a cooling agent for the reduction of varnishes 
it also has excellent qualities. The author takes this 
opportunity of stating that on previous occasions his 
recommendations concerning new and useful materials for 
the paint and varnish industry have been misunderstood 
in some instances, and it is to be hoped that these re- 
marks will not be misinterpreted. Pine oil is a new and 
useful material, but it is by no means a substitute for 
linseed oil or turpentine or any of the other materials now 
on the market. It has properties peculiar to itself, and 
when intelligently used is of considerable value. 

Practically all the pine oil obtainable contains a small 
percentage of water in solution, to which it clings rather 
tenaciously, and it is by no means a simple matter to 
dehydrate this material. A rather complex apparatus for 


PINE OIL 265 


dehydrating the material is necessary with temperature 
control, but the test which the author has devised for 
the determination of water is quite simple. If 5 c.c. of 
pine oil are mixed 9 
with 1 c.c. of a neu- a 
tral mineral oil, like , 
benzine, kerosene, or 
benzol, and a_per- 
fectly. clear solution 
is obtained on shak- 
ing, no water is pres- ~ 4° 
ent; but ib there 1s +0 
any water presentin a 
the pineoilthewater 
appears as a colloid, 
and a milky solution 
is obtained which 
does not’ separate 
after long standing. The fact that pine oil will take up 
a considerable quantity of water and still remain clear 
makes it useful for emulsion paints such as are very much 
in vogue at the present time for the interior of build- 
ings, and it has been suggested that the addition of water 
up to 5 per cent for such a purpose is beneficial on 
new walls. The United States Bureau of Chemistry! has 
developed a method for the determination of moisture 
by the use of calcium carbide; this is being investigated 
by the author but on account of its being a gas-volu- 
metric method it is not quite feasible for general use in 
technical laboratories. 

A number of commercial samples of pine oil were de- 
hydrated and analyzed. The tables following indicate 
the results obtained: — 

1 U.S. Dept. Agriculture, Bureau of Chemistry, Circular 97. 


FRACTIONATION OF Pine O/L 


PER CENT. 
Oo 
ro) 


My 
S 
S 
< 
= 
» 
x 
fC) 
Lo 
ie: 
¢ 


SS 





200 210 220 
DEGREES. -G. 
880 S90 200/910) 9208 7950 240 


No. 103. 


CHEMISTRY AND TECHNOLOGY OF PAINTS 


266 


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o'r6 o'F6 1°88 o'1g 0°39 v-ov 1°S6 ogt Levi ¢L°o IO][OD MVIIS oS£6"0 8 
$°96 $96 $°28 Sol 6°8S S-6¢ * 9°g6 SLI gOc1 L1'0 aq 1978 z7Qe0'0 L 
S:S0 $-S6 0g 9°69 9°9$ gge L°z6 gol zeV1 olo IOJOI MVIIS cs¢6'o 9 
2 rd ah ie eS Seg L-Sg grr 6O-eL1 6r'0 joquiv a[eq 16z6°0 $s 
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S°L6 S°L6 ook g°gS 6°9v bot ¢-L6 SvI beSzr IS°o ayy Jaye geeo'o € 
1°26 26 gos gv Qe £07 £96 S4I V-gir 6z°0 ayy JoywM oynb JON Lzv6o-o Zz 
1°96 1-96 z° LQ aos g cr g lz +°¢6 oLI S°-cv1 gg'0 MOT[OA ATUL YT €zvo-o I 
“siy ze “sry Vz “SIU Q “sy, 9 “sy V “sy Z ‘sty6 “J yutod anyea onyjea oy geo L 
er eee Joye (p) yseTq  autpoy poy IoOjOD ye 13 “ds adits 
Jaye sso] ued Jog ssoy JUID Jog 
a “q 9$9 — eanjzeroduisy WOOT TV (q) yVeq wWrsys EOF 





SLSaL NOILVUOdVAY 
STIQ ANIC 10 SAaSATIVNY — ‘I aTav J, 


PINE OIL 267 


TABLE IJ. — FRACTIONAL DISTILLATION OF COMMERCIAL PINE OIL 








Fraction Total Sp, er. 
Temperature in % distillate I 55 C. 
VTS Oe a las ae a re 2 2 0.882 
eee T CA are ee ee. hs 5 afin Scape 5 7 0.920 
Dae SOG ee he bec ap ewe eee II 18 0.933 
eA AOE EM 8 cas wih Fn seh, bow Soe 10 28 0.939 
Peer eye eS ay. 2 Aiea oe ee 25 53 0.941 
ee ARR Raye, okie ses Nae os a5 88 0.942 
ODE Dy oe 6 04 0.942 
2 whe 9S a a ‘3 95 
ae Ee i yy be acess oS 4 99 





TABLE III. — ULTIMATE ANALYSIS OF PINE OIL 








Sample Number. C. H. O. 
Ceo Re SNS yee oe en 78.1 TT 35 10.4 
B)o Ao te by cles ee AS a 77.0 11.4 10.7 
eM a Pe oR a dic ste Bes 0 US as 77.0 TI51 11.9 
MN Bs eh eyo eee PRY ER os 81.8 10.6 7.6 
REE a on saree, die grey Re 80.9 10.6 8.5 
le Sta SO a eee co nee aera 79.0 II.4 9.6 
PSS RCO eI eg re ee 78.4 £572 10.4 
oS Ewcigc gh 21h Sa eee eine are 79.6 rr-5 8.9 
Oi es eo a 78.3 Liar 10.6 
RA RT tA, Soe een ks Ya Pes 79.0 1i.2 9.8 
Terpineol (theoretical)............... 77.85 ii 10.38 
Preece LUIpentINe. 65. 2. a Fane de 87.7 11.9 
American. turpentine... 6. ...5... 2.65. 87.7 42.1 
Wicod tumpentine:. 0) 2 iF ia Coen 85.7 12.5 304 
Pine vou, tirst-Funnings. 2... ee 84.3 11.8 3-9 


Distillate pine oil, 174 — 195° C....... 82.6 11.4 6.0 





CHAPTER XxX 


BENZINE 


THE petroleum products are used very largely in the 
manufacture of all kinds of mixed paints, the principal 
one used being that known as “benzine.”’ It belongs to 
the series of organic compounds having the general for- 
mula CnHo.+ 2. Although it is frequently added to paint 
in its pure form as a diluent it is just as frequently added 
in the form of a liquid drier which is a solution of the 
original thickened drier in benzine. 

Within the past ten years benzine has been so made 
that its odor is not very apparent, and there is much 
discussion as to whether benzine is a detriment to paint 
or hot. It is hardly necessary to touch upon the moral 
side of this question. If a man should order a paint 
made according to a given specification and free from 
benzine, or to contain only turpentine as a diluent, the 
addition of benzine would be a palpable fraud. It is, 
however, unnecessary to discuss this point. The prin- 
cipal questions for discussion are, first, ““Is a moderate 
amount of benzine harmful to paint?” Second, “How 
much benzine is permissible in paint?” 

Answering the second question first, as to how much 
benzine is permissible in paint, that depends entirely 
upon the paint. A thick, viscous, ropy paint which is 
so difficult to apply that it will not flow evenly is un- 
doubtedly improved by the addition of benzine. It would 
be just as much improved by the addition of turpentine; 
perhaps it would be improved most by the addition of 

268 


BENZINE 269 


kerosene, especially in the case of very quick drying 
paints, since kerosene evaporates more slowly than either 
benzine or turpentine. In the case of such dilution theory 
fails and only practice can dictate how much diluent 
can be added. In the case of a dipping paint where the 
even spreading of a linseed oil paint is desirable, and 
the sudden evaporation of the solvent helps to produce 
a uniform coat, benzine cannot be replaced by any other 
solvent. | 

The argument that is held forth by many, that ben- 
zine is of no value in a structural iron paint for the 
reason that its rapidity of evaporation lowers the dew 
point, as then moisture is deposited as it evaporates, is a 
most fallacious argument, although in theory it is cor- 
rect. Turpentine will do exactly the same thing and so 
will any other solvent, depending entirely upon the 
hygroscopic condition of the atmosphere. If painting be 
done in an atmosphere where the humidity is high and 
the temperature near the dew point, it is always found that 
it makes very little difference what solvents are used, 
the condensation being apparent in any case. The 
metallic structure itself lowers the dew point so that 
the painting is being conducted on a film of invisible 
water, to the detriment of the paint and to the detriment 
of the metal. On the other hand a series of experi- 
ments made on this subject showed that where the dew 
point and the humidity are high, condensation easily 
occurs even though the percentage of moisture in the 
atmosphere is relatively small. (See ‘‘Causes of Rust in 
the Subway,” Journal of the Society of Chemical Indus- 
try, 1905, No. 10, Vol. 24.) A great advantage is to be 
obtained by the moderate use of benzine, for in brushing 
on a quick-drying paint containing benzine the evapora- 
tion carries with it much of the moisture in the paint. 


270 CHEMISTRY AND TECHNOLOGY OF PAINTS 


The low price of benzine in America offers a great 
temptation for its unlimited use. In France and Ger- 
many, where the petroleum products are more expensive 
than they are in America, and more particularly in 
France, benzine is not regarded so much as an adulterant. 
However, the physical effects of benzine have been so 
thoroughly overcome since turpentine has reached such 
an abnormal price, that a number of most excellent 
brands have been placed on the market as substitutes, 
all of which are equal in physical characteristics to 
pure spirits of turpentine. The objection, of course, 
to kerosene as a diluent in paint is that it may carry 
a small percentage of paraffin oil that has a tendency to 
produce a “bloom” on paint and particularly on varnish. 

Quite a large number of petroleum products have 
been placed on the market which are so closely analogous 
to turpentine that were it not for the odor, or lack of 
odor, it would be very difficult to differentiate them. As 
an instance it may be cited that turpentine is a better 
solvent for some of the mixing varnishes and fossil and 
semi-fossil resin driers than benzine, but the newer 
petroleum or paraffin compounds, some of which have had 
marked success, are absolutely identical in solvent power, 
speed of evaporation, and viscosity, to turpentine, and 
while the polymerization acid test would clearly show that 
they are not turpentine, they can by no means be said to be 
inferior in working quality or solvent power to turpentine. 
The method by which these benzines are made consists 
in passing certain paraffin oils over red-hot coke in con- 


junction with wood turpentine. The product which is ~ 


obtained has little or no odor. /Thick or viscous paints, 
particularly the varnish and enamel paints, are so much 
improved by the addition of these materials that even an 
inexperienced painter will notice the free-flowing quali- 


BENZINE 271 


ties of the material to which these diluents have been 
added. 

The petroleum products used in the manufacture of 
paint are principally 62° benzine, which means benzine 
having a specific gravity of 62° Baumé. Some of the 
other naphthas ranging from 71° to 88° are used, but 
these. are so light and bring so much higher prices than 
the 62° that they are not used as much as the 62° naph- 
tha.. The newer grades, however, which approach tur- 
pentine in physical characteristics, must be counted on as 
an important factor in paint on account of the extremely 
high price of turpentine, and the fact that it is strongly 
held in a few hands. On account of the decreasing amount 
of this product, substitutes must be recognized. After 
all, any solvent, whether it be benzine, turpentine, 
naphtha, benzol or acetone, is nothing but a solvent and 
evaporates completely, leaving the other vehicles to pro- 
tect the paint. Of course, too much solvent is a detri- 
ment to paint, no matter what kind it may be. 


SS a ae ee BENZINE ! 


Engler Distillation of Commercial 88° Naphtha 


Sicr, (Westphal) | ake. as. TeheOae (Gok wanna ee 0.651 
IN Mao Wayne waubie Soar t ef 1.36095 
: Temperature % Wt. SpeGrers..0..C. Na 
50° 47.7 0.609 I. 3605 
Oo atOr aS. 29.2 0.65 1.3756 
Poel OO 6.8 0.70 I. 3930 
Residue 1.4 1.4001 


Engler Distillation of Commercial 62° Naphtha 
BDasUil- eG estohal lite wee ae oe TOU eet ae eee 0.732 
NG Core oe etek Sika Oe hands 1.4106 


1 Richardson & Mackenzie, Amer. J. of Sc. XXIX, May, 1g10. 


272 CHEMISTRY AND TECHNOLOGY OF PAINTS 


Temperature % Wt. Sp: Grozo7200Gs Ni@s. 
oO 

50 See Se 

SO stom st 1.2. oy) fe ene I. 3830 
75° to 100° 20.0 0.7029 1. 3956 
100 to 125° ees) 0.7286 1.4061 
125° to 150° 24.6 0.7462 1.4168 
Residue Oi: 2 5k Catan | ere ae 1.4282 


WHITE SPIRIT 


In England and some parts of the continent of Europe, 
turpentine substitute is known under the name of “‘ White 
Spirit.” This name is, however, totally unknown in the 
United States, and while white spirit is a good turpentine 
substitute, it is not the same material as that sold in the 
United States. It has a very much more pungent odor 
and flashes at a lower degree. The United States Navy 
specifications demand a turpentine substitute with a flash 
at approximately 105° F. and white spirit used in Great 
Britain flashes at 75° F. White spirit is usually freed from 
grease or residual oil and distills over completely at from 
TOh tO 2O™ ae 

Much improvement has been made in the production 
of white spirit since the war, for some of the solvents 
which are sold in the British market of the type of white 
spirit are almost odorless. 


CHAPTER XXI 
TURPENTINE SUBSTITUTES ! 


WHEN coal is distilled in the dry form volatile hydro- 
carbon gases are liberated, which when condensed form a 
liquid which has great value in the arts, and is generally 
called crude benzol. Its composition really is about 60 
per cent of benzol, the balance being toluol, xylol and 
solvent naphtha. The latter three are homologues of 
benzol. It is estimated that over forty million gallons 
of these solvents have been wasted in the United States 
in smoke and vapor in the manufacture of coke, but at 
this writing great efforts are being made to collect the 
vapors economically and to put in additional ovens for 
the manufacture of these by-products, so that it is very 
likeiy that both benzol and toluol will soon be sold again 
at normal prices. At this writing both benzol and toluol 
have risen from 25 and 30 cents per gallon to $1.25 and 
$7.00 per gallon respectively, owing to the great European 
war and to the small amount of benzol and toluol manu- 
factured in the United States. These materials have 
been sought for very eagerly for the manufacture of both 
‘ carbolic and picric acids and trinitrotoluol. 


BENZOL 


This material was for many years known under the 
name of benzene, and here it must be noted that the 
benzene which is equivalent to benzol is always spelled 

1 In the chapter on “Turpentine” the author has related how 


turpentine substitutes came into their own on account of the excessive 
price of turpentine. 


273 


274 CHEMISTRY AND TECHNOLOGY OF PAINTS 


benzene, and the light naphtha obtained from paraffin 
crude oil is spelled benzine. 

Benzol is the first volatile liquid which is recovered 
when coal tar is distilled. Benzol when pure is color- 
less. has a pleasant odor, a specific gravity of 0.879 and 
a boiling point of ro1° F. It flashes practically at air 
temperature. It crystallizes into a solid at the freezing 
point of water and has a peculiar analogy to water 
inasmuch as it melts again at about 37° F. It is insoluble 
in water but is soluble in alcohol, ether and petroleum 
naphtha. Its formula is CsHs; it attacks, though it 
does not dissolve, all forms of linoxyn, which it wrinkles 
and removes from the base. It is for this reason that 
it is so valuable as a paint remover. 

Benzol has remarkable solvent properties for many 
things which contain water, such as a number of the 
soaps, and is therefore invaluable to the paint manu- 
facturer when used in small quantities, for it prevents the 
livering or saponification of many of the paints which have 
alkaline tendencies, and which would become unfit for 
use if it were not for the small quantity of benzol 
added. 

The addition of benzol to mixed paints to be used 
for priming purposes has been found to be very advan- 
tageous, on account of the fact that a firmer bond is 
formed between a priming coat and the wood, so that 
when benzol is found in a mixed paint recommended for 
priming purposes it must be looked upon as a valuable 
ingredient. 

The addition of a very small percentage of benzol to 
mixed paints does no harm, but if a paint made with 
benzol and intended as a priming coat be used as a 
finishing coat it is quite likely to attack the ground coats 
and produce a shriveled effect. 


TURPENTINE SUBSTITUTES 275 


The theoretical chemist will sometimes make a mistake 
when he finds benzol in a black mixed paint by reporting 
the presence of coal tar, from the false reasoning that if 
benzol is present coal tar must be present, because benzol 
is a constituent of coal tar. A chemist must, therefore, 
be very careful in drawing such a conclusion, for the 
presence of either coal or pine tar in a paint can be 
determined by other methods. 


TOLUOL 
Formula, CsH;:CHs3 


Toluol is very closely related to benzol, has practically 
the same specific gravity but a trifle lower—.869 to .87 — 
a freezing point of 30° F., and a boiling point of 230°. 
It does not flash at air temperature, and therefore 
is of considerable value where high flash paints are 
wanted. 

In the manufacture of turpentine substitutes out of 
paraffin or petroleum naphthas the addition of toluol is 
of great value, particularly where refractory gums are 
to be dissolved. As for instance, cold petroleum naph- 
tha added to a manila varnish will practically throw it 
out or precipitate it out, whereas the addition of toluol 
prevents this, depending upon the amount of toluol that 
the solvent contains. 

It has been recommended, and from experiments made 
it appears to be a fact, that toluol added to a paint in a 
quantity not over to per cent is of great value in the 
painting of cypress wood, but it is doubtful whether it 
is any better than pine oil, which can be used more 
liberally and which has even more penetrative effects 
and a higher flash point than toluol. 


276 CHEMISTRY AND TECHNOLOGY OF PAINTS 


XYLOL 
Formula, CsH4u(CHs)o 


Xylol really consists of three isomers having boiling 
points of 278° and 287° respectively. It cannot be very 
well separated by distillation. Xylol has all the char- 
acteristics of toluol but is not used to any great extent 
in the paint industry on account of its high price. 


SOLVENT NAPHTHA 


This is a mixture of different hydrocarbon compounds 
which have not yet been very well worked out; but sol- 
vent naphtha has a very disagreeable odor, which no 
one has been able to remove up to the present time, and 
therefore its use in the paint industry is very limited. 
When someone will discover a method for deodorizing 
solvent naphtha it probably will replace many of our 
solvents, as it is really a better solvent than anything we 
know of at present, and even dissolves such materials 
as gutta percha, balatta and many forms of rubber. 
Its specific gravity is the same as that of xylol and toluol, 
but it boils at a much higher temperature, depending 
upon its composition, from 300° F. to 360°. 


CHAPTER XXII 


CoBALT DRIERS! 


THE cobalt compounds which are generally offered on 
the market today may be divided into two classes. In 
the first are cobaltous oxid, acetate, sulphate, chloride, 
nitrate, hydroxid, and basic carbonate. In the second 
class are various grades and qualities of resinates (some- 
times called sylvinates), both fused and _ precipitated, 
oleates or linoleates, oleo-resinates, tungates and resino- 
tungates, besides some other liquid preparations com- 
posed in whole or part of the foregoing. 

From the varnish manufacturer’s standpoint the 

substances in the first division are crude materials which 
are utilized in the production of the compounds in the 
second class, and also in the preparation of some var- 
nishes, liquid driers, drying oils, and the so-called paint 
oils. The materials enumerated under the second class 
are the result of a varnish maker’s labor, and when 
properly made and used in mixtures to which they are 
adapted give very good results. 
The inorganic salts of cobalt do not directly come 
under the scope of this paper, and thus will not be 
directly considered except inasmuch as their use as crude 
material affects the driers into whose composition they 
enter: 

It is only within the past three years that the cobalt 
driers have been offered to the American paint and varnish 

1 By V. P. Krauss, 8th Int. Congress of Applied Chem. From 
the laboratory of Toch Brothers, under the direction of the author. 

277 


278 CHEMISTRY AND TECHNOLOGY OF PAINTS 


manufacturers. Up to the present time their use is not 
general, first, because of the very high price, and second, 
because their use is not thoroughly understood. Many 
experimenters have had unsatisfactory results and there- 
fore refused to further consider the introduction of 
the new material. Furthermore, not all of the cobalt 
driers, whether liquid, paste, or solid, now offered for 
sale, are properly made and truly adapted to the pur- 
poses for which they are recommended. This situation, 
in addition to unsatisfactory results obtained by some 
of those experimenting, would naturally have a retarding 
effect on the introduction of a new type of material. 
The salts of cobalt which are at our disposal in com- 
mercial quantities are all of the cobaltous or divalent 
type. It has been found that although they can be 
readily used in the manufacture of driers and worked 
like the various compounds of manganese, lead, zinc, 
calcium, aluminium, etc., the organic compounds formed, 
which are the basis and active principles of the so-called 
driers, are not efficient while in the cobaltous state. 
The cobaltic combinations, however, are very active 
driers, and it is for the formation of trivalent cobalt 
compounds that we strive in the making of driers. This 
transformation can be effected in several ways. By blow- 
ing cold, heated, or ozonized air through the hot cobal- 
tous drier stock, or by the introduction of liquid or solid 
oxidizing agents. The use of cold or even heated air is a 
very long and tedious operation if carried out to the 
extent to which it is necessary in order to get the maxi- 
mum strength in the drier, and greatly adds to the cost 
of an already expensive material. The use of the liquid 
or solid oxidizers can be carried out successfully and in a 
comparatively short time, although even when great care is 
exercised the batch of material is in danger of catching fire. 


COBALT DRIERS 270 


Since driers are used in a number of industries in 
which drying oils form part of the material produced, 
and since the operating methods of the various manu- 
facturers are widely divergent, the siccatives or driers 
adapted to each will in many instances show widely 
different characteristics, not merely in form but also in 
composition. 

Since the paint manufacturer and also the practical 
painter who mixes his own paints from paste colors and 
raw or treated oil are the principal consumers of what 
are generally known as driers, the materials adapted for 
their use may be first considered. The driers will, in 
practically all instances, be in the liquid state either very 
fluid, of heavy consistency or of a semi-paste nature. 
In composition, they will mostly consist of resinates, 
tungates, oleates, or linoleates, or combinations of the 
three. For the drying of linseed oil, when the proper 
driers are selected, little or nothing can be asked in ad- 
dition to those known at present. When the general lead, 
manganese and other prevalent metallic driers are well 
chosen raw linseed oil can without any difficulty be made 
to dry by the addition of from 5 to 10 per cent or even 
less, the time of drying under average weather conditions 
being from to to 24 hours. By the use of cobalt driers, 
the same drying effect can be obtained when only from 1 
to 3 per cent of a liquid drier is used. The author is not yet 
prepared to say positively what the ultimate effect of cobalt 
driers is upon paint films, but from the experiments made 
it is deduced that cobalt has not the harmful progressive 
oxidizing action that some of the usual manganese-lead 
compounds have. It has also been noticed that although 
a cobalt drier may be fairly dark in color, it will not have 
as darkening an effect as one of the usual driers of like 
color would have upon a white paint. The cobalt driers 


2890 CHEMISTRY AND TECHNOLOGY OF PAINTS 


likewise show the same phenomena as some of the 
others when used in excessive amount; that is, that 
although the paint film will set up well in the usual time 
the drying action apparently reverses and the film remains 
tacky. 

The terms applied to liquid driers are often uncer- 
tain and apt to be misleading. There are no general 
standards for strength or consistency, and, it must be 
admitted, many of the materials found on the market 
contain more volatile thinners than is conducive to 
obtaining a maximum drying effect with a minimum 
quantity of drier. 

The value of the cobalt specialties depends not on 
their power to dry linseed oil, but on their ability to 
make the lower priced semi-drying oils act like it. 

Soya, fish, and even corn and cottonseed oil are 
adaptable for use in paint, and when correctly treated, 
increase its durability. 

In the making of waterproof fabrics, insulating coat- 
ings, etc., both liquid and solid driers are used. In the 
linoleum, oilcloth, patent leather, artificial leather and 
similar industries, the semi-liquid, paste, and solid driers 
are in demand since for these products the manufactur- 
ers cook the oils and varnishes in their own factories. 

The paste and solid driers must essentially be con- 
sidered under the caption of crude materials because 
they must be churned or cooked in the oils or varnishes 
in which they are used. 

The methods of making both the solid and liquid 
driers are in general similar in the first stage of the 
process, and thus may be described under the same 
headings. 

Resinate of Cobalt; Precipitated and Fused. — This is 
correctly made by saponifying rosin or colophony with 


COBALT DRIERS 281 


caustic soda or sodium carbonate, care being taken to 
avoid an excess of the reagent, and then precipitating 
with a solution of some salt of cobalt. The chloride or 
sulphate serve best for this purpose. The precipitated 
resinate, or as it is sometimes called, rosinate or sylvin- 
ate, must then be thoroughly washed, and then pressed 
and dried. ‘This will yield a pinkish, fairly fluffy powder 
when ground, which will readily dissolve in oil at a low 
temperature. The fused variety is made by melting the 
dried resinate in a kettle and then pouring into cooling 
pans. The operation is performed more rapidly by 
taking the cakes from the presses and driving off the 
water and fusing in one operation. 

Cobalt Oleates or Linoleates.—The basis of this class 
is generally lnseed oil, although walnut, perilla, soya, 
and some other oils may be used. The oil is thoroughly 
saponified with caustic soda, and, like the resinate, pre- 
cipitated with a salt of cobalt. The material is then 
carefully washed and pressed. It may be melted to form 
a dark viscous heavy fluid. 

Several samples of cobalt linoleate examined 
consisted of bodied linseed in which small amounts 
of inorganic cobalt salts had been dissolved. Another 
was of the same order with the addition of volatile 
solvents. 

True linoleate of cobalt, when fused with varnish 
gums and dissolved in volatile oils, yields an excellent 
drier. 

Oleo-resinates. — This type of drier is made by melting 
together the precipitated resinate and linoleate, some- 
times with the further addition of fused fossil gum- 
resins. 

Tungate of Cobalt. — Like the linoleates, the tungate 
of cobalt is made by saponifying pure China wood oil 


282 CHEMISTRY AND “LECHNOLOGY OF srATN gS 


(tung oil) with caustic soda, care being taken to avoid 
excess of caustic, and then precipitating with a salt of 
cobalt. The tungate is then washed thoroughly, pressed 
and generally dried and fused. Great care is necessary 
in the preparation of a tungate since it oxidizes very 
rapidly, and the oxidized material is useless. 

Like the linoleate of cobalt, the tungate may be fused 
with the resinate to form what may be called a resino- 
tungate. 

In general the foregoing substances are incorporated 
in oils by means of heat, the combining temperature be- 
ing between 300° and 500° F. The amount necessary will 
vary from about $ per cent to 5 percent. In order to make 
liquid driers, the paste or solid driers can be melted alone 
or in combination with gum-resins, bodied linseed oil, or 
both, and then thinned to liquid consistency with volatile 
oils. 

Among other cobalt salts, some of the chemical manu- 
facturers offer the acetate, with directions for its use as a 
drier. All agree that between two and four tenths of 1 
per cent are necessary to dry linseed oil. The oil should 
be at a temperature between 300° and 4oo° F., and be 
carefully stirred until all the salt is dissolved. Soya and 
China wood oil may be similarly manipulated. 

It is still a little too soon to make a positive state- 
ment as to how oils thus treated with the acetate with- 
stand wear and exposure. 

Cobalt oxide, like the acetate, can be directly added 
to oil during boiling. It, however, dissolves slowly and 
necessitates heating to high temperature; the resulting 
product is also very dark, and mostly consists only of 
bodied oil. Rosin also will directly combine with cobalt 
compounds on heating together in a suitable kettle or 
container. The product possesses a number of objec- 


COBALT DRIERS 283 


tionable features. It still is mostly unchanged rosin, 
has become much darker and lost considerably in weight 
due to volatilization. The effect on oils of quite a number 
of cobalt compounds was tried, but none equal in efficiency 
to those described in the foregoing was found. 

One of the best methods for the manufacture of cobalt 
drier is to keep it im statu nascendi until it is ready for 
manipulation. This is best brought about by using ap- 
proximately the following formula. 


(1) 25 lb. caustic soda, 76° Bé 

(2) 20 gal. hot water 

(3) 20 gal. China wood oil 

(4) 5.5 lb. cobaltous nitrate or sulphate, 
concentrated solution. 


The caustic soda is dissolved in a varnish kettle in 
20 gallons of hot water, and allowed to boil, then the 
China wood oil is stirred in slowly, and this forms a soap. 
To this must be added to gallons of hot water in order to 
make it perfectly fluid. In another kettle the cobalt 
nitrate and hot water are dissolved, and slowly poured 
into the China wood oil soap mixture and allowed to boil, 
adding water until 4o gallons of water have been slowly 
added. The cobalt soap is then a bluish crumbly mass 
which precipitates out and is strained and thrown into 
another varnish kettle, half full of boiling water. This 
‘dissolves out all the sodium salts which are contained in 
the mass as a by-product and leaves the China wood oil 
cobalt soap. If this is filtered through two thicknesses of 
cheesecloth a cheese-like mass is obtained which should 
be rolled up into balls about the size of a fist, approximately 
r pound, and placed in a barrel half full of water. When 
ready for use, three of these balls may be added to 100 
gallons of linseed oil or China wood oil as a drier, and if 
added in small pieces no excessive foaming will take place, 


284 CHEMISTRY AND TECHNOLOGY OF PAINTS 


At temperatures over 200° C. this soap is taken up by the 
oil, and forms an excellent drier. 

In enamel paints of the long oil variety, particularly 
those that contain large quantities of zinc, 14 pounds of 
this soap to 100 gallons of oil will dry perilla oil or linseed 
oil at room temperature over night, but it has been found 
that this drier becomes less and less effective the older it 
becomes in the presence of zinc. It is therefore of advan- 
tage to keep it in its nascent condition in order that the 
best results may be obtained. 

For textile and special paint work more rapid drying 
is desired. The same formula can be used for making both 
lead and manganese soaps. It has been found where 50 
per cent of cobalt drier is used and 25 per cent of lead 
and manganese added to the oil or varnish, excellent results 
are obtained. 


CHAPTER: XXIII 


COMBINING MEDIUMS AND WATER 
COMBINING MEDIUMS 


In certain classes of mixed paints, particularly house 
paints which are made of corroded lead, sublimed lead, 
barium sulphate, etc., there is a likelihood or tendency of 
the pigment to settle. This is more marked in the case 
of corroded lead than in any of the other pigments. To 
prevent this, In a measure, water is added, and up to a 
certain percentage (1 per cent) both the manufacturer and 
the consumer have accepted the fact that water is not 
injurious when added for the purpose of combining the 
paint; but beyond this percentage its effect is likely to be 
injurious. 

Sometimes for the sake of an argument, but more 
often for the sake of making a paint which contains no 
more water than the natural moisture of its constituents, 
a manufacturer feels the necessity of adding a combining 
medium other than water to prevent the paint from 
settling hard in the package. Among these are gutta- 
percha solutions, solutions of balata, para-rubber, gum 
chicle, etc. The rubber solutions mentioned serve their 
purpose very well without injuring the paint, and the 
percentage used is so small that it may be considered 
negligible. This, however, is not true of many of the 
mixing varnishes which are made by varnish manufactur- 
ers who have no experience in the manufacture of paint. 


They sell rosin yarnishes neutralized with lime, lead, or 
285 


286 CHEMISTRY AND TECHNOLOGY OF PAINTS 


manganese, and while they assist very well in combining 
the lead with the oil, the wearing quality of the paint is 
proportionately reduced. 

Within the last few years a new combining medium 
has appeared on the market which in itself is an improve- 
ment on all paints. It is made by melting a mixture of 
a resin (free from rosin or colophony) and heavy linseed 
oil, and reducing with China wood oil and naphtha. 
Where a manufacturer uses a combining medium of this 
character the paint becomes more viscous as it grows 
older, and when it dries it produces a satin-like gloss and 
shows fewer brush marks than a paint containing water. 


WATER IN THE COMPOSITION OF MIXED PAINTS 


The question of how much water shall be added to 
mixed paints, or how much water mixed paints shall 
contain, either added or incidental, is not fully decided 
upon, as there is a difference of opinion as to its value, 
and likewise a difference of opinion as to the amount 
necessary for certain purposes. There are some paints in 
which as high as 2 per cent of water is necessary, and in 
other paints less than 1 per cent is purposely added. 
That water is of great benefit in certain paints cannot 
be disputed, one large railway corporation permitting 
the addition of 1 per cent of water to its mixed and 
paste paints. 

A chemist in making an examination of a mixed paint 
must necessarily be careful in giving an opinion as to the 
amount of water in the paint, and great judgment must 
be used in a report. For instance, a paint, made accord- 
ing to a certain specification, containing a large mixture 
of Venetian red and yellow ochre, might contain very 
nearly 2 per cent of moisture, which was a part of the 


COMBINING MEDIUMS AND WATER 287 


composition of the pigment. Then again, linseed oil fre- 
quently contains more than a trace of water, which the 
manufacturer cannot extract nor can he afford the time 
necessary to allow the water to settle out of the oil. A 
mixed paint should not contain over 1 per cent of water, 
for it is unnecessary to add more than this amount to 
any paint. 

The proper benefits derived from the addition of water 
to a pure linseed oil paint are suspension of the pigment 
and improvement in its working quality. Take the case 
of artists’ tube colors which lie on the dealers’ shelves 
for years and which are prone to get hard and likely 
to separate so completely that the color will be found 
on one side of the tube and the oil be entirely free on the 
other. Water is an absolute necessity in this case and is 
an improvement for both seller and user. The colors 
made with the correct addition of water are known 
fe ee and artists: prefer a color which “piles” 
properly. 

There are many ways of adding water to a paint. 
In some instances the required amount of water, together 
with the oil and the drier, are placed in a churn or mixer 
and the paste paint stirred in. Where materials like 
calcium sulphate, calcium carbonate, ochre, Venetian red, 
slicate of magnesia, silicate of alumina, white lead, etc., 
are used, there is no necessity for adding any combining 
material which will form a soap with the linseed oil, 
there being sufficient action between these materials and 
the water. It is an additional advantage that there is 
less likely to be complete saponification in a mixed paint 
to which no ‘‘emulsifier’”’ has been added. 

The following materials are used for emulsifying 
paints: 


288 CHEMISTRY AND TECHNOLOGY OF PAINTS 


Saturated solutions of hypochlorite of lime. 

Five per cent solution of carbonate of soda. 

One-quarter of one per cent solution caustic soda. 

One per cent solution of carbonate of potash. 

Emulsion mixtures of half water and half pine oil. 

Solutions of hypochlorite of lime containing twenty per cent 
wood alcohol. 

Ten per cent solution of borax. 

Five per cent solution zinc sulphate. 

Seven per cent solution lead acetate. 

Five per cent solution manganese sulphate. 

Solutions of ordinary laundry soap or rosin soap in half 
alcohol and half water. 

Weak solutions of casein dissolved in ammonia water. 

Ordinary lime water emulsified with linseed oil. 


There is no license whatever for the addition of much 
water to paint. Some authorities state that as high as 15 
per cent is permissible, but the author does not by any 
means subscribe to that, as 14 gallons of water in 100 
gallons of paint are far in excess of any desirable amount. 
Three-quarters of 1 per cent or at most 1 per cent 
would probably be a maximum, and as an explanation 
of this it must be understood that materials like ochre, 
clay, silicate of magnesia, white lead, calcium sulphate 
and many of the pigments which contain moisture or 
water of crystallization may carry a small amount of 
water into paint. 

Yet there may be cases where water is permissible up 
to 5 per cent, but only for interior purposes. Flat wall 
paints which have a tendency to settle hard can be 
emulsified so as to prevent them from settling, and in a 
case of this kind where the wear of the paint is not taken 
into. consideration there may be some excuse or license 
for the addition of water. 


COMBINING MEDIUMS AND WATER 289 


To detect water in paint, particularly in light-colored 
paints, is a comparatively simple matter. The method 
devised by the author is almost quantitative for some 
purposes. The first method ever published by the 
author consisted in placing a strip of gelatin in a mixed 
paint. When a measured or weighed amount of mixed 
paint was taken and the strip of gelatin allowed to remain 
immersed for twenty-four hours a fairly correct quantita- 
tive determination was obtained. Another method de- 
scribed some years ago involved the use of anhydrous 
sulphate of copper, a bluish white powder, which on the 
addition of water returns to the natural dark blue color 
of crystallized copper sulphate. 

The author has, however, devised the scheme of 
using a glass plate and mixing a paint with a dyestuff 
such as “Erythrosine B.”’ When about § gram of the 
dye and 5 grams of mixed paint are rubbed together 
with a palette knife on a sheet of glass, a paint con- 
taining no water will produce a distinct pearl-gray color; 
if there is water in the paint the mixture changes almost 
immediately to a brilliant cerise red, and if there is much 
water in the paint (over 2 per cent) the color changes 
into a crimson, so that the reaction is clearly marked. 
The test must not be allowed to stand more than four 
minutes, since even paints which contain no added water 
but which naturally contain traces of moisture will begin 
to change into a rosy color, in which the presence cannot 
be reported. In red, black or dark colored paints Ery- 
throsine B is just as indicative of water in paint, par- 
ticularly when the mixture is viewed by transmitted light. 
Even in the case of black paint the erythrosine emulsion 
paint will produce a beautiful purple color. 


290 CHEMISTRY AND TECHNOLOGY OF PAINTS 


Emulsifiers have been used for hundreds of years, and 
it is well known that prior to the artistic work of the 
brothers Van Eyck, in the fourteenth and fifteenth cen- 
turies, mediums of egg and water to which oil was fre- 
quently added, were regularly used. 

Eliminating any discussion as to whether paint should 
contain water or not, if it be added it is best to use it 
with a harmless emulsifying agent such as pine oil. The 
addition of all of the metallic salts like silicate of soda, 
lead acetate, caustic soda, and the zinc salts is not to be 
recommended, because the resulting paint does not by any 
means give as satisfactory results as paint that contains 
no water. 

The use of oxidizing materials like hypochlorite of 
lime is never to be recommended, for, in case emulsion 
pamts containing oxidizing materials are used on steel, 
violent rusting will ensue. If water is to be used in some 
of the interior flat whites it has a distinctive value in the 
prevention of settling and the obliteration of brush marks, 
and for that pine oil is the best material. The only ma- 
chine necessary for the purpose is a rapid agitator, one 
that makes more than 50 revolutions per minute. A 
favorite formula is as follows: 


100 lb. asbestine, whiting or clay 
10 gal. water 
5 gal. pine oil. 


The resulting semi-paste is used in the proportion of 2 
gallons to 100 gallons of paint, thus making about 1 per 
cent water in the finished paint. 

In the textile industry, the favorite material used for 
emulsifying is casein which has been digested in ammonia 
water. One pound of casein, free from borax or phosphate 
of soda, is mixed with one gallon of 20° ammonia water, 


COMBINING MEDIUMS AND WATER 291 


and allowed to stand over night. The next morning this 
will assume the condition of a glue solution. Fifty pounds 
of whiting, two gallons of oil and 1o gallons of water are 
mixed with this casein solution and heated until nearly 
all the ammonia is driven off. This is then rapidly agi- 
tated for one hour, and the mass is set aside and used as 
is necessary as an emulsifying agent. Ammonium tannate, 
clay, water and linseed oil is a harmless emulsifying formula 
and the ammonium oleates and ammonium stearates are 
also to be recommended, but where their use is beyond 
5 per cent they are more than likely to produce flat effects. 
However, sometimes this is found desirable. 


CHAPTER XXIV 
FINE GRINDING 


THERE is a great difference of opinion on the question 
of how paints should be ground, and a careful canvas on 
this subject reveals the fact that most paint manu- 
-facturers believe that all paints’ should be very finely 
ground. This is a great error, for there are many con- 
ditions where a paint should be slightly coarse in order 
to give proper results, for if paints do not have a slight 
amount of coarseness, or ‘“‘tooth”’ as it is called, one coat 
will not hold successfully on the other, and it is for the 
very reason of producing a mechanical bond that fillers 
are used which have a distinct grain. Without making 
any general rule on the subject, all priming coats should 
have sufficient tooth to enable the succeeding coat to 
hold. 

Those familiar with the subject are aware of the 
fact that a gloss coat on a gloss coat very frequently 
peels, and the same is sometimes true of a gloss coat on a’ 
priming coat which is too finely ground. This does not 
apply to a finishing coat, because the finer a finishing 
coat the longer it lasts and the cleaner it remains, for a 
coarse finishing coat will hold dust and dirt which even a 
heavy rainstorm will not always dislodge, while a smooth, 
finely ground finishing coat acts like a glaze and remains 
clean until it perishes. It may therefore be taken as a 
general statement that priming coats should be slightly 


coarse and finishing coats should always be fine. 
2092 


FINE GRINDING 2093 


If you take the case of the finishing of a very fine 
object like a piano or an automobile, rubbing varnishes 
are used on the undercoat, and these varnishes are 
scarified with pumice stone for two reasons: first, so as 
to smooth the coat thoroughly because the succeeding 
coat when applied will then itself produce a smooth and 
glossy effect, and secondly, so that the next coat which 
is applied can bind itself mechanically to the undercoat. 
If, therefore, rubbing is a practice where varnished objects 
are to be finished, it must be taken as a rule that where 
paints are applied and rubbing is not practiced a slight 
grain is of great benefit, so that the question of fine 
grinding does not apply to every case. 


CHAPTER XXV 


THE INFLUENCE OF SUNLIGHT ON PAINTS AND 
VARNISHES ! 


Ir may properly be said that direct sunlight has a 
very destructive action on paint and varnish films, and 
the author had noted as far back as 15 years ago that 
many of the paint materials that were perfectly water- 
proof in places where sunlight never reached became 
permeable to water and disintegrated very rapidly when 
exposed to direct sunlight. As an example of this, it 
might be cited that pure asphaltum, when applied in a 
good continuous coat on cast iron pipes in a cellar, will 
last from three to four years, yet the same asphaltum 
when applied on the roof of a building will show al- 
most complete decomposition within 20 days. In order, 
therefore, to determine the cause, the first experiments 
with a series of bitumens were made as follows: Sheets 
of clean steel and wood were painted with a variety of 
bitumen compounds and exposed to direct sunlight under 
various colored glasses, finally reduced to the three 
colors, violet, green, and red; for obvious reasons these 
three served all purposes. It was found at the end of 
four weeks that the bitumens exposed under the blue 
rays showed marked signs of decomposition, those under 
the green showed some signs, and those under the red 
none whatever. The same experiments were tried again 
by cementing the glass to the painted surface, when 
little or no decomposition followed in any case. A large 

! Reprinted from the Journal of the Society of Chemical Industry, 


April 15, 1908. No. 7, Vol. XX VII, Maximilian Toch. 
204 


INFLUENCE OF SUNLIGHT ON PAINTS AND VARNISHES 295 


variety of experiments was then tried by mixing the 
bitumens with various pigments, and a preservative 
action was obtained in direct ratio to the pigment used, 
so much so that a sample of paint made to contain 80 
per cent of bitumen, 15 per cent of linseed oil, and 5 per 
cent of finely divided carbon, showed only slight deterio- 
ration at the end of six months; this was easily accounted 
for by the fact that the finely divided carbon prevented 
the absorption of many actinic rays. While these 
experiments were very conclusive, it was necessary to 
determine the cause, and to this end a large variety of 
experiments was conducted, all of which were productive 
of excellent results. 

All asphaltums are bitumens, but all bitumens are 
not asphaltums, and it is necessary to look into the com- 
position of the asphaltums which decompose in the sun- 
light and of those resins which do not. The difference 
between a resin and an asphaltic bitumen may generally 
be stated as follows:— Asphaltums and bitumens are 
composed principally of carbon and hydrogen, whereas 
the resins are semi-fossilized, and composed of carbon, 
hydrogen, and oxygen. Asphaltums, whether they be 
natural or artificial, consist largely of hydrocarbons of 
the series of CaHon-2, CoHen—1, CoHon-s, etc., and according 
to Clifford Richardson! and others, these hydrocarbons 
are probably polymethylenes. From a large number of 
combustion determinations made with bitumens, it may 
be safely stated that many of the bitumens are probably 
polymethylenes of various series, as above. There are, 
of course, substances in bitumens such as sulphur and 
nitrogen, which probably exert very little influence on 
the material from an actinic point of view. Assuming, 


1 See “The Modern Asphalt Pavement” and “Origin of Asphalt,” 
by Clifford Richardson. 


206 CHEMISTRY AND TECHNOLOGY OF PAINTS 


therefore, that the hydrocarbons are of the character 
described, we -should have under the combined action 
of the oxygen of the air and the actinic rays of the light, 
sometimes, in conjunction with moisture, a favorable 
condition where oxygen would combine with hydrogen, 
and carbon be set free. Therefore, if this reaction takes 
place, all bitumens in a short time ought to become car- 
bonized and deposit relatively pure carbon on their sur- 
faces, and this is exactly what takes place, the action of 
the sunlight probably resulting in a combination of the 
_ hydrogen with oxygen, and a deposit of what appears to 
be carbon takes place. If this, then, is the first lucid 
explanation of the decomposition of bitumens in sunlight, 
it is the explanation of the cause of the valuelessness of 
pure bitumens as protective paints for exterior purposes. 
Even the addition of a small amount of bitumen to a 
large percentage of otherwise good paint will result in the 
decomposition of this paint when exposed to the direct 
action of moisture and light. 

We have no such action when materials are used which 
are glycerides of fatty acids, such as fish oil, Chinese 
wood oil, and linseed oil. Indeed, any one of these three 
oils are light-proof in a very large degree, and fish oil 
and Chinese wood oil are both heat-proof and light-proof. 
Linseed oil, however, unless prepared with fossil resins, 
is not water-proof, but fish oil is more water-proof, and 
Chinese wood oil most water-proof of all. At the same 
time, pure Chinese wood oil is less light-proof, next comes 
fish oil, while linseed oil is most light-proof, and there 
would appear to be an established ratio that a paint or 
varnish containing the least amount of oxygen is the 
least light-proof and the most water-proof, and the paint 
containing the largest amount of oxygen is most proof 
against light, and least water-proof. 


INFLUENCE OF SUNLIGHT ON PAINTS AND VARNISHES 297 


In conclusion, and as evidence of the correctness of 
these statements, if a sheet of metal or wood be painted 
with asphaltum or bitumen-paint and exposed to sunlight 
and air, the coating will be rapidly decomposed, and after 
a lapse of 20 days probably carbon will be set free. 
At least, this is a deduction from the nature of the 
bitumens. Minute scrapings from the surface of exposed 
bitumens show that the principal constituent is carbon, 
and, whereas the original material contains much less, 
the exposed bitumen shows over 95 per cent of carbon, 
the remainder being principally hydrogen, with a small 
difference, which is evidently oxygen.’ This shows that 
the general reaction tends to produce carbon. 

The painting of concrete to preserve it against the 
action of moisture and frost is destined to become as large 
an industry as the painting of wood, and those who have 
tried asphaltum paints for this purpose have already 
found to their sorrow that disintegration takes place in 
a very short time, even though the material be perfectly 
proof against the alkaline action of the lime in the con- 
crete, and as linseed oil paint is rapidly destroyed by 
concrete itself, owing to the interaction of the lime and 
the linseed oil, we have to look for other materials with 
which we can coat concrete in order to preserve not only 
its appearance, but the very structure itself. 

- Regarding the action of sunlight on pigments, it is 
well known that lithopone is rapidly acted upon by light, 
and direct sunlight turns it a dark gray, but frequently 
overnight the color leaves it and it is brillant white 
again in the morning. English vermilion (mercuric 
sulphide) is also acted upon by sunlight, and forms first 
a brown compound and then a black compound of mer- 
cury. This has been regarded as mercurous sulphide or 
as a sub-sulphide of mercury, but on this question the 


2098 CHEMISTRY AND TECHNOLOGY OF PAINTS 


writer has doubts. Some of the oxids of iron, par- 
ticularly the bright red ferric oxids, are affected by light, 
and a compound results which from bright red turns to 
brown, probably a change tending towards the formation 
of ferrous oxid. 

We know that a large number of the organic dyestuffs 
tend to bleach in the sunhght, but sunlight alone is 
never very active regarding the decomposition of colors 
when air is excluded, for even mercury vermillion is 
regarded as permanent when it is covered by a coat of 
varnish. This is largely true of the organic lakes and 
finer colors used for coach painting. Linseed oil itself 
is bleached by sunlight, but this is a chemical change 
produced by the actinic rays in which the green chloro- 
phyll is changed to pale yellow. 

The fading, darkening and discoloration of paints is a 
phenomenon not clouded in mystery as it formerly was. 
A pure bright ferric oxid, of the Indian red type, when 
applied either in the form of a shingle stain or in the form 
of a paint made with linseed oil, darkens considerably on 
exposure to sunlight. ‘This influence is more evident when 
linseed oil is used as a vehicle, but not marked when the 
China wood oil varnish is used. It is, therefore, reasonable 
to infer that the ferric oxid changes into a higher oxide 
and the higher oxids are not bright red, but brown. 

Red lead which should be an absolutely permanent | 
color to light, turns a grayish white on exposure, which is 
primarily due to the action of sulphuric and sulphurous 
acids in the air. It is really not a fading reaction but the 
formation of a microscopically encrusted salt on the 
surface, which masks the original color. 

Chrome greens of the reduced variety which are mix- 
tures of chrome yellow and prussian blue based upon 
fillers and reinforcing materials such as barytes, whiting, 


INFLUENCE OF SUNLIGHT ON PAINTS AND VARNISHES 299 


calcium sulphate, etc., are never permanent when exposed, 
and invariably bleach. There are many instances where 
the color changes into an ochery olive color and whether 
this is a Brownian movement of the filler, or an action of 
sulphuric acid, has not yet been definitely determined. 
It may possibly be both, for it is a well known fact in 
portrait painting that a white underground eventually 
works its way partially to the surface, or near the surface, 
and no other explanation can be had of this excepting that 
it is a Brownian movement. 

Para and toluidine reds when reduced with whiting and 
barytes sometimes change within a year to a straw color, 
which is not due to any actual fading of the dye itself. 
The peculiar part of these changes is, and this applies also 
to the green pigments, that when the so-called faded 
suriace is rubbed or wiped with a rag dipped in linseed 
oil, the color comes back to its pristine brilliancy. On 
the other hand, when these reduced pigments, such as 
chrome green, para red and toluidine red, are coated with a 
China wood oil waterproof varnish shortly after they are 
thoroughly dry, the apparent fading or bleaching does 
not take place. It is, therefore, reasonable to infer that 
this type of fading is only a masking of the color, due 
most probably to both chemical influence and the Brownian 
movement of the filler. 

The decomposition of lake colors in sunlight is a differ- 
ent type of reaction and due entirely to the action of the 
rays of light from green to violet, and the direct actio1 
of ultra-violet light. Carmine, for instance, even under 
glass will fade out completely in three months. The 
alizarin lakes in concentrated form will not be affected 
at all, but many of the other aniline dyes, such as the 
basic and the azo types, fade partially in three months and 
are therefore useless for the painting of automobiles, 


300 CHEMISTRY AND TECHNOLOGY OF PAINTS 


railroad signals and sign work. Once the lake colors 
fade, it is not possible to bring them back to their original 
condition. 

It is possible to test colors for permanency to light by 
means of ultra-violet light in less than an hour. The iron 
arc and the carbon arc are also very effective, even though 
they be enclosed in glass, but it is always wise in making 
these tests to moisten the color with water as the reaction 
takes place much quicker in water than it does in a dry 
atmosphere. 


CHAPTER -XXVI 


PAINT VEHICLES AS PROTECTIVE.AGENTS AGAINST 
CORROSION ! 


A CAREFUL search of the literature of the past twenty 
years has failed to reveal anything like a systematic 
investigation of the relative value of different vehicles 
used in the manufacture of paints for structural steel 
and the prevention of corrosion. There are a few isolated 
cases in which boiled linseed oil,? Kauri linseed oil var- 
nish* and spar varnish as protective coatings on structural 
steel were studied. For many years past much has been 
written and many investigations have been made on the 
protective quality of the pigments, but no one has appar- 
ently made any study of the vehicles. 

It is quite obvious that without a vehicle a pigment is 
useless, and the author knows of no instance where a pig- 
ment could be used alone, with perhaps the single exception 
of Portland cement, if that may be classed as a pigment; 
even then, Portland cement would be useless unless water 
were used asa vehicle. The example need hardly be called 
to your attention of taking a dry pigment and using water 
as a vehicle to show you that when the water evaporated 
it| would leave the pigment, and the pigment in turn 
would leave the metal; and yet, to the best of the author’s 


1 Journal of Society of Chemical Industry, June 15, 1915. No. 
11, Vol. XXXIV, by Maximilian Toch. 

ooG Von Kreybig, Farben Ziz.,°17, 1766-8; “J..N- Friend, 
Carnegie Scholarship Report, Iron and Steel Inst., May, 1913, pp. 1-0. 

3 Address of Prof. A. H. Sabin before American Society of 
Civil Engineers, Nov. 4, 1896, reported in Engineering News, July 
28, 1808. 


301 


302 CHEMISTRY AND TECHNOLOGY OF PAINTS 


knowledge, nobody has paid any attention to the very im- 
portant réle that is played by the vehicle itself. There is 
an old proverb which says, ‘One hand is useless, for one 
hand washes the other,” and it seems that the same is 
true with reference to vehicle and pigment, for one is of 
little value without the other, and if any value is to be 
attached to either of them the vehicle has by far the 
advantage, because there are some vehicles which protect — 
for a considerable length of time. 

With this end in view exposure tests were made in 
1913, in which fifty-two steel plates (in duplicate) were 
carefully: freed from grease by washing with benzol, 
dried, sanded, and rubbed clean with pumice, and then 
coated with all the paint vehicles or protective vehicles 
to the extent of fifty-two in number, many of which, of 
course, are seldom, if ever, used alone, and some of 
which are failures a short time after they are put on. 
_ However, the author wanted to do this thing thoroughly, 
and for this purpose selected the same quality of steel, 
known as cutlery steel, which has been used by him for 
many years for his exposure tests. It is a steel which 
rusts very rapidly. 

Those plates must be eliminated which have shown no 
rusting in the year and five months that they have been 
exposed. These were coated with the paraffin or machin- 
ery oil compounds, and it would be poor advice to any 
engineer to coat steel with paraffin compounds, for the 
method of cleaning before the application of any good 
paint would have to be very carefully followed out, 
since no protective paint would hold on steel that re- 
tained the least trace of a paraffin coat. Then the 
paraffin, or non-drying oils, all collect a great deal of 
dirt, which showed that this would have to be entirely 
removed before any paint could be applied. 


PROTECTIVE AGENTS AGAINST CORROSION 303 


Plate No. 41 showed excellent results, and a material 
of this kind would not be so very expensive where en- 
gineers demand that steel be coated with a clear liquid 
in the shop so that the steel may be inspected in the 
field. This was composed of half spar varnish and half 
stand oil. Stand oil is practically a polymerized linseed 
oil. Linseed oil when heated to 550° F., with a drier 
like Japanner’s Prussian brown or borate of manganese 
will produce a very thick viscous liquid, which is largely 
used as a patent leather finish. This can be reduced 
with 50 per cent of thinner and still have the fluid- 
ity or viscosity of raw linseed oil, and is, therefore, 
inexpensive. | 

Plate No. 50 was coated with a material containing 
to per cent of paraffin oil, which might be classed as 
an adulterated linseed oil, and while it showed up very 
well, it could not be recommended because on an exposed 
structure like a bridge a coat of good protective paint 
would not adhere very thoroughly. 

Plate No. 52 has taught a valuable lesson with regard 
to the use of raw China wood oil which is heated to a suf- 
ficient degree of heat to take 10 per cent of a tungate 
drier, and then thinned with 15 per cent of benzine. This 
made a material which is hardly more expensive than 
good, boiled linseed oil, and left a most excellent surface 
for repainting. In fact, this has proved itself the equal 
of plates No. 22 and No. 23, with the addition of a better 
surface for repainting. 

Plate No. 46 was coated with kettle-boiled linseed oil, 
and is very good, but this material might be regarded 
by some engineers as too expensive for application, as 
it took all day to make this oil. A carefully selected 
linseed oil was chosen to start with, to which was added 
5 per cent of litharge and no other drier. This oil dried 


304 CHEMISTRY AND TECHNOLOGY OF PAINTS | 


very badly, but when it did dry produced a good flexible 
film which lasted. This must not be confounded with 
the average boiled linseed oil of commerce. 

The various coatings used in these exposure tests 
have been divided according to their protective value 
into five classes: 

t and 1 b— Those vehicles which have little or no 
value for the prevention of rusting. | 

(a) The raw and refined drying and semi-drying 
vegetable oils. (Plates Nos. 1, 7, 8, 13, 35, 30) 47) 400) 

(b) The same oils to which to per cent of drier 
had been added. ‘(Plates Nos. 2, 3, 4; 0,50) to.muaemuee 
14, 34.) 

(c) The more or less volatile paint thinners. (Plates 
NoS.i17:718,-10, 207325) 

(d) Solutions of celluloid and pyroxylin. (Plates Nos. 
24, 25.) 

(ec) The liquid (at room temp.) paraffin oils. (Plates 
Nos. 21, 30.) 

2— Those vehicles which showed some degree of 
protection, though not very much at best. 

(a) Wood-oil varnishes containing a certain percentage 
of rosin. (Plates Nos. 26, 20.) 

(b) Copal-wood-oil varnishes. (Plates Nos. 27, 28.) 

(c) Varnishes made from linseed oil which had been 
thickened and oxidized by blowing with air, oxygen or 
ozonizediair.. (Plates (Noss32a 7) 

This compared with the results obtained below with 
cooked-oil varnishes proves conclusively that the film 
yielded by a blown oil is not nearly as waterproof and 
resistant to severe weather conditions as that formed by 
a boiled or polymerized oil. 

3 — Varnishes or varnish mixtures which protected 
the steel very nicely as long as weather conditions were 


PROTECTIVE AGENTS AGAINST CORROSION 305 


not severe and temperature changes not very rapid and 
pronounced. (Plates Nos. 39, 40, 42, 43, 44, 45, 49.) 

4— The semi-solid and solid paraffin oils. These 
show a very high degree of protection from rusting. 
Pa teseNOS. £5. 31.) 

5 — Those varnishes and vehicles which afford a 
high degree. of protection against .corrosion. To be set 
down in this class a material must be extremely water- 
proof; it must dry with a film which is very elastic and 
yet tough in order to be able to withstand “‘ weathering.”’ 
A film which cannot remain intact against condensed 
moisture, snow and ice and despite comparatively wide 
and sometimes rapid changes in temperature (as between 
day and night even in rather warm climates), will of 
necessity afford very little protection for the steel to 
which it is applied. As the table on pages 307-308 shows, 
this class comprises: 

(a) Spar varnish. (Plate No. 16.) 

(b) Varnishes made from linseed oil, or China wood 
oil, which have been thickened by a heat process. (Plates 
Nos. 22, 23, 52.) 

(c) Open kettle-boiled oil. (Plate No. 46.) 

In Plate No. 50 we find a rather anomalous case. 
It seems that raw linseed oil which has been dried with a 
small percentage of a liquid paraffin oil proved to be an 
excellent coating for rust prevention. 

The addition of any paraffin or non-drying oil, even 
in such a small quantity as is shown in Plate No. 50, 
is dangerous in case repainting becomes necessary. Al- 
though the matter is not settled in the author’s mind as to 
whether linseed oil and paraffin oil dissolve in each other, 
his idea at present is that, although they apparently make 
a clear solution, separation takes place. Several experi- 
ments were conducted, and it was found that a film of lin- 


306 CHEMISTRY AND FECHNOLOGY OF PAINTS 


seed oil which contains paraffin oil in some quantities when 
apparently dry shows minute globules of paraffin oil in 
wet condition when the film is heated over 100°C. A 
film of linseed oil containing to per cent of paraffin oil 
after it is six months old can be extracted with naphtha 
and shows uncombined paraffin oil. These experiments 
prove conclusively that it is dangerous to mix a paraffin 
oil with linseed oil for any purpose, excepting where 
it is not necessary, or not the intention, to repaint 
subsequently. 

Note: All the photographs submitted (see pages 309- 
310) were taken during December, 1914. 


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CHAP LER = XOSVil 
THE ELECTROLYTIC CORROSION OF STRUCTURAL STEEL? 


ENGINEERS have commented publicly on the electro- 
lytic corrosion of structural steel, particularly those parts 
known as grillage beams, supporting columns and base 
posts, which are either in the ground or surrounded by 
concrete and partly above the ground, with a view of 
determining beyond question at which of the poles corro- 
sion occurs, and whether one pole is more active than the 
other. 

The author performed an experiment by taking two 
sheets of high grade watch spring steel, which is ex- 
tremely susceptible to corrosion, and connecting them 
with the ordinary bluestone telegraphic cell. Voltmeter 
and ammeter were placed in the circuit and the two pieces 
of steel buried up to 5 in. in sand. Careful observation was 
made every day to see that the current was uniform, and the 
sand was first moistened with salt water and then contin- 
ually moistened with distilled water so that the same 
strength of salt solution was maintained. This experi- 
ment was conducted for too days, and assuming that the 
current travels from plus to minus, or from anode to 
cathode, the anode being connected with the copper and 
the cathode being connected with the zinc, corrosion was 
noticed almost immediately at the anode, and the plates 
showed violent corrosion at the anode and practically no 
corrosion at the cathode. These plates indicated some 

1 By Maximilian Toch. Reprinted from Proceedings of 
American Society for Testing Materials, Volume VI, 1906. 

311 


a2 CHEMISTRY AND TECHNOLOGY OF PAINTS 


slight corrosion on the cathode, which, however, was 
principally chemical corrosion. 

The strength of the current was .o5 of a volt and the 
distance between the plates, varying in the damp sand, 
was 15 inches, and the amperage varied from .o2 to .o5. 

The current was measured by a “Pignolet,” direct 
reading, continuous current volt-ammeter, and the amount 
of current which produced this corrosion was exceptionally 
small. 

Another experiment was tried exactly in the same 
manner, for a shorter period of time, but instead of using 
two plates, three plates were used, the third one being 
designated as the “free”? plate, in which chemical corro- 
sion had full sway. At the end of six days these plates 
were removed; the anode showed marked corrosion, the 
cathode plate showing practically no corrosion at all, and 
the ‘“‘free’ plate showed a fair average between the 
cathode and the anode, and it can be deduced that the 
difference between the cathode and the anode corrosion 
is equal to the “free” corrosion. In other words, there 
is many times more corrosion on the anode than there is 
on the “free” plate, and no corrosion on the cathode 
plate. 

The rust first produced was the green ferrous oxid, 
Fe(OH),, which, being a very unstable product, was 
quickly converted in the air into Fe,O;, N(H,0). 

The current was .1 of a volt and .1 of an ampere 
which produced this result. The salt solution was four 
times as strong as that produced in the first experiment. 

A third experiment was, however, of the greatest im- 
portance, owing to the fact that the author attempted 
to imitate the conditions exactly as they existed in 
buildings. The same kind of steel was taken and bedded 
in various mixtures of concrete, starting from neat 


PEeCLROLY TIC CORKOSION OF STRUCTURAL STEEL -°313 


cement and going up to 1:3:5. There is a well-known 
law in physical chemistry that reactions which take place 
with an increase of pressure are retarded by an increase 
of pressure, and the question has come up as to whether 
it is possible for steel to corrode when surrounded by 
concrete, many engineers holding that the alkaline na- 
ture of the cement will prevent the corrosion, and others 
holding that in conjunction with this condition the pres- 
sure exerted by the concrete prevents chemical decom- 
position. The author is glad to be able to throw some 
light on this subject, and the following experiment was 
carried out: 

In the first place cement was taken of known com- 
position, agreeing practically with the definition as quoted 
in the Journal of the American Chemical Society, July, 
1903, when the question of the permanent protection of 
iron and steel by means of cement was thoroughly 
gone into. The cement for these experiments was 
what might be termed the tri-calcic silicate and 
calcium aluminate. This is in contradistinction to the 
general classes of Portland cements containing dicalcium 
ferrite as a part of their composition and free calcium 
sulphate in excess. A cement of the calcium aluminate 
class, free from iron and free from calcium sulphate, is a 
well-known protector of steel and iron against corrosion, 
and this class of cement was used in these experiments. 
The pieces of steel were connected up with six elementary 
cells of sufficiently high voltage and amperage, and it was 
impossible to get a direct reading from the volt-ammeter, 
the instrument being too sensitive. The seven parts of 
cement containing the steel strips were then put into the 
circuit and wet every few hours with solutions of 5 per 
cent sodium chloride and 1 per cent nitric acid, and water, 
in order to increase their conductivity and produce corro- 


314 CHEMISTRY AND TECHNOLOGY OF PAINTS 


sion as rapidly as possible. The average strength of the 
current was .o5 volts and .o5 amperes throughout the entire 
experiment. Corrosion was immediately noticed at the 
anode pole, and the pat of neat cement, which should have 
protected the steel most perfectly against all kinds of corro- 
sion, showed a hair line split colored with rust at the end 
of the third day, which demonstrated that the chemical 
reaction of rusting had taken place at the anode; that the 
molecular increase had likewise taken place, and the pres- 
sure caused by the molecular increase had split the block. 
The steel in each alternate pat was painted half the length 
which was embedded in the cement with an insulating 
paint of known composition having a voltage resistance of 
625 volts per millimeter. The results obtained after these 
various briquettes were broken open demonstrated that 
electrolytic corrosion takes place most violently at the 
anode unless the steel be coated with an insulating 
medium. 

Cement, concrete, or even neat cement, is therefore no 
protection against electrolytic corrosion, unless the steel be 
insulated as heretofore mentioned, and there was absolutely 
no corrosion where coated with insulating material. It 
must be noted that the cathode in all these experiments 
was perfectly free from any signs of oxidation. 

The result of this entire series of experiments is to 
prove conclusively that electrolytic corrosion of struc- 
tural steel embedded in concrete or sand takes place only 
at the anode and there with great violence; and further- 
more, that the cathode is protected by the electrical cur- 
rent. The popular impression that cement is a protector 
against all kinds of corrosion is fallacious. The anode 
does not only rust very violently, but a molecular in- 
crease of volume may take place which will split the con- 
crete shell. 


ELECTROLYTIC CORROSION OF STRUCTURAL STEEL aus 


Another conclusion arrived at is that the electrolytic 
rusting of grillage beams of buildings need not be feared 
if the structural steel be protected by a good insulating 
material, but the insulating medium should form a bond with 
concrete. 


CORROSION OF STEEL IN CONCRETE ! 


When steel corrodes its volume increases in relation to 
its molecular weight, and this is as 112 is to 214. This, of 
course, varies with the nature of the corrosion, and I am 
taking yellow rust as a standard. The increase in its vol- 
ume produces pressure, and if there is sufficient pressure 
to counteract the increase, there can be no corrosion, on the 
well known chemical theory that reactions which produce 
pressure are retarded by pressure. 

Tradition has taught us that concrete prevents corrosion 
of steel, and progress is retarded on account of tradition 
in many instances. 

If a steel bar is imbedded in concrete sufficiently deep 
and kept back from the exterior face sufficiently far so that 
the weight of the concrete is greater than the pressure pro- 
_ duced by corrosion, there will be no corrosion, but if the 
bar is near the surface so that water and air can reach the 
steel and react, you not only have corrosion, but the pres- 
sure produced by it splits off the surface of the concrete. 
The general statement, that concrete prevents corrosion 
is not correct, in fact, concrete may accelerate cor- 
rosion if the amount of lime liberated is below a given 


1 Extract from a lecture delivered before the Concrete Institute, 
Chicago, February 25, 1925. 


316 CHEMISTRY AND TECHNOLOGY OF PAINTS 


strength.! Take the case of a steel drum in which ammonia 
is shipped. Just as long as the ammonia is of sufficient 
strength no corrosion takes place on the inside of the drum 
because the alkali inhibits it, but empty the drum and fill 
it with water, or reduce the ammonia below a given strength, 
and you produce corrosion even though the liquid is strongly 
alkaline... If you take Portland cement, and mix it with 
two parts of sand, and then imbed a piece of bright, clean 
steel in it, one quarter of an inch below the surface, you can 
submerge this experiment in all kinds of corrosive liquids, 
and no corrosion of the steel takes place for two reasons, 
first, because a 1-2 mixture sufficiently trowelled is imper- 
meable, and secondly, because the amount of alkali gene- 
rated by a rich mixture of that kind is sufficiently great to 
prevent corrosion; but if you take a steel bar imbedded in 
a I-25-5 mixture you will have corrosion, or you will pre- 
vent corrosion depending upon the distance that the steel 
is from the surface. 

Every engineer, of course, understands that there are two 
elements that produce rust; one is air (oxygen), and the 
other is water, but pure air that contains no water is non- 
corrosive, and distilled water or boiled water that contains 
no air is non-corrosive. A piece of steel exposed to the air 
of New Mexico or Arizona remains bright for many months 
because the air does not contain sufficient moisture to pro- 
duce rust. I believe engineers will agree with me, that the 
proper place for reinforcing rods or bars to obtain the 
greatest compressive strength should be near the surface. 
Unless the surface be waterproofed, or the bars treated so 
that they will not corrode, the same effect will be produced 
as is shown in photographs 1, 2 and 3. 

If cement wash, as an exterior finish, is an added Bree 


' Gorrosion of Iron & Steel; dilute Alkaline Solutions; J. Newton 
Friend; See also — Heyn & Bauer; Cribb & Arnauld. 


BLECTROLYTIC CORROSION OF STRUCTURAL STEEL sy 


tion on a concrete building, how much more of an added 
protection would an acid resin paint be with a waterproof 
coating; but the only trouble with a cement wash is, that 
it may or may not set, and if it does not, you will simply 
have a coating of dust. 

It costs very little to paint steel reinforcing rods, but an 
alkali-proof paint which adheres to concrete should be used; 
but where an engineer has any objection to the use of a pro- 
prietary material, he can get good results by making a 
mixture of one part of Portland cement, and one part of 
very fine sand, mixed to a creamy consistency with lime 
water. This will assure sufficient alkali to inhibit corrosion. 

There are in addition to the yellow rust, two other types 
of rust. The black and the brown, both of which are mag- 
netic (yellow rust is not magnetic), and frequently these 
peculiar brown and black scales dispersed with some of the 
yellow rust, will form layers, often 1/2’’ thick, and event- 
ually scale and drop off. There are many examples of this, 
particularly in subterraneous buildings and this reaction has 
been noted even in concrete where the concrete was par- 
ticularly lean and porous. 

Where there is a surface flow against concrete, the cem- 
entitious lime is leached out in time. The solvent action 
of sea water is much greater than that of pure water, as is 
evidenced by the experiment that 1-7/1o pounds of lime 
are soluble in 1000 pounds of pure water, and that 2-8/10 
pounds of lime are soluble in tooo pounds of salt water. 
Many abstruse and complex theories have been advanced 
on the erosion of concrete in sea water, but it is most likely 
that this simple explanation of solubilities covers the case. 

A method for the prevention of corrosion of steel and 
concrete is to apply a proper coating on the exterior of 
concrete and prevent the access of air and water. Such a 
coating must, of course, be light-proof and should not be 


318 CHEMISTRY AND TECHNOLOGY OF PAINTS 


neutral, but may be composed of a paint containing a 
resinous acid, which will combine with the free lime. 
Another method has been proposed which while fairly 
good, is always empirical, that is, the spraying of the sur- 
face before painting with either zinc sulphate or zinc chlor- 
ide. The action of zinc chloride seems to have the advantage 
of being slower, because it is a more deliquescent salt, but 
the objection to both of these compounds is that one never 
knows how much to use because the amount to be used is 
dependent upon the amount of free lime present and any 
excess is likely to destroy the paint film applied afterwards. 
Straight linseed oil paints are never good on raw concrete, 
and when a zinc salt is used in proper proportions, it will 
give effective service, particularly if spar vanish is added 
to the linseed oil paint. Perhaps the least harmful of any 
of the coatings for the preparation of concrete walls or sur- 
faces is a mixture of fluosilicate of zinc and sodium, or 
magnesium, and the most simple test of determining whether 
a wall will take paint without the decomposition of the oil, 
is to apply a test strip of diluted prussian blue, and if the 
blue turns brown in spots or entirely, it shows that the wall 
is still alkaline, but if the blue remains in its original con- 
dition, it shows the wall is neutral, and ready for paint. 


CHAPTER XXVIII 


PAINTERS’ HYGIENE 


ALL paints should be regarded as poisonous, and even 
though it may be understood as a general rule that 
materials like ultramarine blue are non-toxic or that 
silica has no effect upon the system, it is unwise for the 
paint manufacturer to permit his men either to breathe 
these in dry dust form or to allow his workmen to eat 
their meals before washing themselves thoroughly. We 
are all very familiar with the fact that white lead pro- 
duces lead poisoning, but in any well-regulated factory 
there is no excuse for this, and the amount of lead 
poisoning produced in factories like the large lead manu- 
factories in the United States is reduced to a minimum 
because the workmen are looked after most thoroughly. 
Workmen who are employed in a dusty atmosphere should 
always wear respirators, and workmen who work with 
lead products should not be permitted to grow mous- 
taches, as the dust of many of the poisonous pigments 
settles in the moustache and is then absorbed through 
the nose. White lead under the finger nails is absorbed 
into the system, and a careful watch of these things will 
prevent any disease among the men; but all in all there 
is more sensationalism and hysteria on this subject than 
is warranted by the results, for in paint factories where 
sufficient care is taken there is practically no illness 


among the men. 
319 


320 CHEMISTRY AND TECHNOLOGY OF PAINTS 


Paint vapors are all toxic, and any painter who is 
ignorant enough to apply any paint material in a closed 
room does not deserve to be a painter. Even materials 
like pure spirits of turpentine, which are known to have 
medicinal qualities, when breathed in large quantities are 
supposed to produce headache and vertigo, and the fumes 
of benzol, benzine and alcohol give the same results; 
therefore all people who apply paint should do so in well- 
ventilated rooms. Large vats which are varnished on the 
interior like brewers’ vats, or water tanks which are 
painted on the inside, are generally ventilated by the 
engineers in charge by having fresh air pumped in con- 
tinually to the men from the top and by simply pumping 
out the vapors from below, as practically all of the 
materials used in the manufacture of paint give off vapors 
which are heavier than air. 

Paint vapors are also inflammable, and any fire 
resulting from careless smoking or throwing lighted 
matches near paint is likely to produce disastrous results, 
but much information has been disseminated on this 
subject, particularly through the railroads, who now 
demand caution labels printed on each package before 
it is shipped with the result that many lawsuits which 
were instituted formerly against the manufacturer are 
not permitted today. The same is true with regard 
to the vapors arising from paint. It has been a practice 
among certain questionable lawyers to institute suits 
against paint manufacturers for illness, headaches, nausea, 
vertigo and such other physical ills as have resulted from 
the fumes of paint, and few of these lawsuits have ever 
been tried, because the paint manufacturer in former 
times has been inclined to settle a suit of this kind 
rather than go to court, but these cases are not as 
frequent as they formerly were on account of the wide- 


PAINTERS’ HYGIENE cre! 


spread knowledge of the subject. Fumes arising from 
paint are not dangerous in the open air, but if a painter 
is careless in a closed room it is certainly his fault, and a 
man who knows so little about paint should not be per- 
mitted to use it. 


CHAPTER XXIX 


THE GROWTH OF FUNGI ON PAINT 


FUNGI must not be confounded with bacteria. Bac- 
teria are invisible micro-organisms, and whether they 
thrive on paints has never yet been established. Their 
existence in oil or paint media has never been proved. 





No. 106. GREEN FUNGUS X500. 


Experiments made by the 
author in which various 
bacteria were grown in 
gclatin or agar agar have 
demonstrated that when 
turpentine, benzine, linseed 
oil, varnish or paints of 
any character, excepting 
those containing water, were 
added, they rapidly per- 
ished. Fungi, however, are 
totally different organisms. 
A fungus is derived from a 
spore which floats in the 


air and which practically is a microscopic seed. When 
this falls on fertile ground it sprouts and becomes a white 
downy mass, which is known as the hypha. This 
downy mass later on assumes a color, which may be 
either gray, green, yellow or black, and is known under 
the popular title of mildew, which is in reality a fungus 
or micro-organic growth of the vegetable type. 

What may be poisonous to a human being is evi- 
dently non-poisonous or neutral to a fungus, for fungi 


322 


THE GROWTH OF FUNGI ON PAINT. 323 


can grow and do grow on practically all of the barium 
precipitates, which are known to be highly poisonous. 
A fungus needs both warmth and moisture for its 
propagation, and so we will frequently find that on the 
south side of a house at the seashore, where moisture will 
collect and the temperature will be fairly uniform, fungi 
wll sprout on a painted surface and frequently destroy 
the paint. This is more noticeable in the tropics than it 





No. 108. ASPERGILLUS NIGER 
— Photomicrograph xXt1o00, 
old fungus found on paint. 





No. 107. BLACK FUNGUS X125. 


is in the North, and more noticeable in the European 
countries than it is in America, for the humidity in the 
United States is way below normal for more than half 
of the year whereas the humidity is fairly constant in 
Europe and in the tropics. Some of these fungi are very 
disagreeable, particularly the black types, which will 
grow on the interior of houses, and which always propa- 
gate better in a cellar than they doin a garret, for light 
has a tendency to kill them. 

The fungi that are found on paint may be classified 
into the following varieties: 


324 


CHEMISTRY AND TECHNOLOGY OF PAINTS 


t. Penicilium Crustaceum types, of which there are 
many varieties, but all of which are greenish or olive 


grayish. 

2. Aspergillus Niger, 
which is distinctly black 
and very tenacious. 

3. Rhizopus Nigricans, 
which is brown and black, 
and which appears gener- 
ally in the Fall of the year. 

4. Aspergillus Flavus, 
which is yellow and orange, 
and which grows freely on 
a putrid soil or near de- 
caying vegetable matter. 


It must be generally understood that the use 
fungicides is not always to be recommended, for 


ASPERGILLUS FLAvVUS— 


No. Ifo. 
Photomicrograph  X600, yellow 
fungus frequently found in brew- 
eries and dairies, thriving on paint. 








No. 109. ASPERGILLUS NIGER — Photo- 
micrograph xt1o0o, black fungus fre- 
quently found on paint in cellars. 


of 
in 
breweries, malt houses, 
rooms which have swim- 
ming pools, and_ cellars 
which have been used for 
storage, these fungi grow 
at times, and it seems as 
if there is nothing which 
kills them. The best way 
to get rid ofsthem isero 
wash the surface copiously 
with soap and water and 
then spray a mixture of car- 
bolic acid and formaldehyde 
and afterward bichloride of 
mercury, but a man apply- 


ing a material of this kind must use a mask and a 


respirator. 


THE GROWTH OF FUNGI ON PAINT 325 


Many a complaint has reached a paint manufacturer 
that his paint has turned black in spots under the eaves 
of a roof or in a ground- 
floor room, and the manu- 
facturer on account of 
ignorance has supplied 
fresh paint free of charge, 
or the painter has done 
the work over again, when 
Beearmatter of fact. the 
fault was due entirely to 
fungus growth. It is well, 
therefore, for the paint 
chemist to familiarize him- No. 111. Craposporrum Hersarum — 
self with at least these Photomicrograph x6co, a pale fungus 
few fungi, as they are the ”" Oe 
principal types which flourish on paint. 

For the prevention of fungus on paint, all the zinc 
salts and all the zinc pigments are excellent. A one per 
cent solution of bichloride of mercury can also be recom- 
mended where its poisonous effect has no influence. Copper 
salts, particularly the cupric salts, are all fungus preventives 
and fungicides, and in a damp dark cellar where white- 
wash, kalsomine, or linseed oil paint, or paint of any 
description is used, a spray of lime copper solution usually 
prevents the formation of fungus. Carbolic acid, in fact, 
all the phenols and all the cresols are much weaker in their 
fungicide property than copper, mercury and zinc salts. 
Bordeaux Solution is an excellent primer on cellar walls. 





CHAPTER XXX 


PHYSICAL EXAMINATION AND TESTING OF PIGMENTS 


Many methods have been described for the routine 
testing of dry colors by comparison with standards and 
the methods given here are the best and most approved 
for practical use, taking into consideration simplicity, speed, 
uniformity and accuracy of results. 


STANDARDS 


A set of all the pigments used should be kept in tightly © 
covered four-ounce bottles of the “‘shellac”’ type, preferably 
of amber glass, and arranged in order on shelves con- 
veniently near the slab and balance. If larger quantities 
are found advisable, they should be stored away elsewhere 
in cans. 

The standards, selected according to the requirements 
of the consumer, should not be made excessively difficult 
to match without considering the general conditions of 
their sources of supply and availability, as ideal colors 
are impossible to obtain at all times. New standards must 
be adopted from time to time as conditions change. 


REQUIREMENTS OF PIGMENTS 


The principal requirements of a paint pigment are 
purity of tone, tinctorial power (strength), smoothness 
and uniformity of texture, permanence to light, age and 
other extraneous conditions, opacity, and compatibility 


with the vehicles and other pigments with which it is to 
326 


PHYSICAL EXAMINATION AND TESTING OF PIGMENTS 3 27 


be mixed. Other characteristics are often desirable in 
dry colors for use in other industries, for example, opacity 
is desirable in a paint color, but transparency is often 
wanted in such uses as printing inks, stains and crayons. 


SHADE AND STRENGTH RUB-OUTS 


Shade. — A weighed amount of the standard is placed 
on a level slab of heavy plate glass or white marble and 
sufficient pale linseed oil is added to produce a stiff paste 
when rubbed with a flexible steel spatula or palette knife. 
The oil is added by means of a dropper or dropping bottle 
and the number of drops carefully noted. Care is taken 
to gather the pigment neatly, occupying a small area 
of the slab and rubbing not more than is necessary to pro- 
duce a uniform paste. 

The paste is then rubbed with a glass muller using a 
uniform slight pressure and a_ back-and-forth, slightly 
circular motion, the idea being to grind over the entire 
amount of paste with each complete rub. After 25 rubs 
the paste is gathered in a pile and given 25 more rubs. 

The procedure is then repeated using the sample to 
be tested, the same amount of oil is added regardless of 
the consistency of the resulting paste and the two rub-outs 
are spread on a strip of glass side by side, their edges just 
touching each other. . Pure white glass of uniform thick- 
ness 1s used, generally microscope slides or cleaned photo- 
graphic plates, and the comparison is viewed by daylight, 
artificial light including the so-called daylight lamps being 
usually unsatisfactory. For the routine testing of many 
pigments mulling is unnecessary and a thorough rubbing 
with the spatula will suffice, but a large number of them, 
notably red lakes and chrome greens, show a marked 
difference when rubbed unequally. When a pigment is 


228 CHEMISTRY AND TECHNOLOGY OF PAINTS 


to be used in water, varnish or other medium it is often 
rubbed out in it instead of linseed oil. 

Strength. —o.1t gm. of the color is rubbed out with 
2 gm. of French process zinc oxid, a standard can of which 
is kept on hand for the purpose. A measured amount of 
oil is used as described above. For prussian blues, ultra- 
marine and the blacks, the zinc is added in the proportion 
of 50 to 1 and for whites and pale yellows a standard 
prussian blue is used in the same proportion. 

The above figures are merely given as a guide and 
are usually varied according to the user’s preference or the 
strength of his standards. The reduction, however, should 
be enough to disclose all the tone qualities and allow slight 
differences in strength to be magnified enough to make 
them easily perceptible without reducing the standard 
to such a pale tint that weaker colors will show up too 
pale to get an idea of relative strengths. Strength rub-outs 
are always mulled carefully and if there is any streaking 
they are given additional mulling until the mixture is 
homogeneous and the color fully developed. 


TEXTURE, UNIFORMITY AND PURITY 


The simplest method of getting comparisons with 
standards for these properties and the one to which most 
of the published accounts seem to give the least attention, 
is microscopic examination. A microscopic view of the 
sample and the standard simply rubbed on halves of the 
same slide with a little water or alcohol will disclose more 
than many of the intricate methods sometimes used. 
With a little experience the appearance of the inert fillers 
such as asbestine, barytes, silica, etc. may be made familiar 
and the presence of their crystals in colors immediately 


PHYSICAL EXAMINATION AND TESTING OF PIGMENTS 329 


- recognized. For the examination of the inerts themselves 
the microscope is invaluable. 

In the case of the earth colors and some of the coarser 
artificial mineral colors a sufficient difference of texture 
will be apparent by the degree of grittiness under the 
palette knife. 


CHAPTER XXXII 
ANALYSIS OF PAINT MATERIALS 


ANALYSIS OF WHITE LEAD 
Gravimetric Methods — Estimation as PbSO, 


Lead. — Dissolve 1 g. in dilute acetic acid, filter, wash 
and weigh the insoluble residue. ‘To the filtrate add to 
c.c. of dilute sulphuric acid (1:1) and evaporate on the 
steam bath. Allow to cool, dilute cautiously to 100 C.c., 
add to c.c. of alcohol and stir well. Filter on a Gooch or 
alundum crucible, wash with water containing 1 per cent 
of sulphuric acid and to per cent of alcohol, and finally 
with alcohol alone. Dry at 110° C. 

Lead sulphate is appreciably soluble in concentrated 
sulphuric acid and slightly soluble in water. It is practi- 
cally insoluble, however, in 1 per cent sulphuric acid and 
in alcohol. It is very soluble in hot, concentrated am- 
monium acetate solution. 


Estimation as PbCrQO, 


Treat 1 g. in a beaker with hot water and just suf- 
ficient acetic acid to dissolve the white lead, using no 
more than 5 c.c. of acetic acid in excess. Filter off from 
the insoluble residue. Dilute to too c.c., heat to boiling 
and add an excess of a neutral, saturated solution of 
potassium dichromate solution. Allow to cool. Filter 
on a Gooch or alundum crucible, wash and dry at 130° C. 


Volumetric Methods — Estimation as Molybdate 


Dissolve 0.5 g. of white lead in 5 c.c. of concentrated 
hydrochloric acid by boiling. Add 25 c.c. of cold water 
330 


ANALYSIS OF PAINT MATERIALS 331 


and proceed as indicated below, under “Standardization 
of Ammonium Molybdate.” 

Lead is precipitated as PbMoO, by a standard solu- 
tion of ammonium molybdate from hot solutions slightly 
acid with acetic acid. The solutions required are: 

(a) Ammonium molybdate — Dissolve 4.25 g. in 1 litre of water 
(b) Tannic acid solution — Dissolve o.1 g. in 20 c.c. of water 

Standardization of Ammonium Molybdate. — Weigh off 
about o.2 g. pure lead foil in a small Erlenmeyer flask 
and dissolve in 6 c.c. of nitric acid (1:2). Evaporate 
the solution just to dryness. Treat the residue with 
30 c.c. of water and 5 c.c. of concentrated sulphuric acid 
and shake well. The precipitated lead sulphate is allowed 
to settle, filtered and washed with dilute sulphuric acid 
(1:10). Filter and precipitate are placed in an Erlen- 
meyer flask and boiled with to c.c. of concentrated 
hydrochloric acid until completely disintegrated. Then 
add 15 c.c. more of concentrated hydrochloric acid, 25 c.c. 
of cold water and neutralize with ammonia until slightly 
alkaline to litmus paper. Reacidify with acetic acid. 
Dilute to 200 c.c. with hot water and heat to boiling. 
Titrate, using the tannic acid solution as outside indicator, 
until a brown or yellow coloration is obtained with the 
latter. 

Precautions. — Titration must be carried out hot, at 
about 90° C. If the solution should cool down in the 
course of titration, reheat it. Here, as in the case of the 
titration of zinc with potassium ferrocyanide, the scheme 
of dividing the solution into two unequal parts may be 
used. 

To determine the excess of ammonium molybdate 
necessary to affect the indicator, place in an Erlenmeyer 
flask 25 c.c. of hydrochloric acid, neutralize until slightly 
alkaline to litmus, then reacidify with acetic acid. Dilute 


332 CHEMISTRY -AND TECHNOLOGY OF PAINES. 


to 200 c.c., heat to boiling, and add ammonium molybdate 
drop by drop until the outside indicator is affected. 

Antimony and bismuth do not affect the results 
obtained by this method. Barium and strontium give 
very low results, while calcium yields but slightly low 
results. The alkaline earth sulphates tend to retard the 
solution of the lead. This difficulty can be overcome by 
thoroughly washing the lead sulphate and then boiling it 
with sufficient ammonium acetate. 

Carbon Dioxid and Combined Water. —t1 g. of white 
lead is weighed off in a porcelain boat. The latter is 
then placed in a combustion tube and heated in a current 
of dry air free from carbon dioxid. The water is col- 
lected in calcium chloride tubes, and the carbon dioxid 
in potash bulbs or soda lime tubes. 

Carbon dioxid may be determined by evolution by 
treating white lead with dilute nitric acid. Use a reflux 
condenser in connection with the evolution flask and dry 
the carbon dioxid by passing through calcium chloride 
before absorbing in the potash bulbs or soda lime tubes. 


Basic’ LEAD SULPHATE 


Lead and Zinc (gravimetric). — Digest 1 g. for ten min- 
utes in the cold with 20 c.c. of 10 per cent sulphuric acid. 
Filter, keeping most of the residue in the beaker, and 
wash twice by decantation with 1 per cent sulphuric acid. 
The filtrate from the sulphuric acid teatment is re- 
served for the determination of zinc which is carried out 
by any of the methods outlined under “Zinc Oxid.” 
Preferably precipitate as phosphate. Calculate the zinc 
to ZnO. 

Dissolve the residue in the beaker with hot concen- 
trated slightly acid ammonium acetate solution pouring the 
solution through the filter. Wash the latter with ammo- 


ANALYSIS OF PAINT MATERIALS 333 


nium acetate and then with hot water. Dilute to 200 c.c., 
add an excess of a neutral saturated solution of potassium 
dichromate and bring to boiling. Allow to cool, and filter 
on a Gooch or alundum crucible. Dry at 130° and weigh 
as PbCrQk. 

Lead (volumetric). — Treat 0.5 g. sample with 30 c.c. of 
water and 5 c.c. of concentrated sulphuric acid, and 
proceed as outlined under ‘Estimation as Molybdate.” 

Sulphates.! — Dissolve 0.5 g. by boiling in a mixture of 
25 c.c. water, Io c.c. aqua ammonia and enough con- 
centrated hydrochloric acid to give a slight excess. Dilute 
to 200 c.c. and add a piece of pure thick aluminium foil 
large enough to nearly cover the bottom of the beaker. 
This should be kept at the bottom by means of a glass 
rod. Boil gently until the lead is precipitated. When 
the lead no longer adheres to the aluminium, the precipi- 
tation may be considered complete. Filter and wash 
with hot water. A little sulphur-free bromine water is 
added to the filtrate, the latter is boiled, and sulphates 
determined by precipitation with barium chloride in 
the ordinary way. 

If desired the sulphates may be determined as indicated 
under Analysis of ‘Zinc Lead.” 

Sulphur Dioxid. — Digest about 2 g. in the cold with 
5 per cent sulphuric acid, and titrate with = iodine solu- 
tion, using starch as indicator. 


ANALYSIS OF ZINC LEAD 


Lead. —1 g. of the material is heated on the steam 
bath with 20 c.c. of hydrochloric acid (1:1) and 5 g. 
of ammonium chloride. The solution is diluted to 250 
c.c. with hot water and boiled. This treatment should 
suffice to dissolve a pure zinc lead. 


! Holley, “Analysis of Paint and Varnish Products,” 1912, p. 104. 


334 CHEMISTRY AND TECHNOLOGY OF PAINTS 


The insoluble residue, if any, is filtered, weighed, and 
examined for impurities. Neutralize the filtrate with 
ammonia, reacidify slightly with hydrochloric acid, and 
precipitate the lead with hydrogen sulphide. 

Allow the precipitate to settle, filter off the liquid, 
and wash the precipitate several times by decantation 
with hydrogen sulphide water. The precipitate is finally 
dissolved in hot, dilute nitric acid, treated with an excess 
of sulphuric acid, and evaporated to SO; fumes. 

Allow to cool, dilute cautiously with too c.c. of cold 
water, filter off the precipitated lead sulphate on a Gooch 
crucible, wash several times with dilute sulphuric acid, 
and finally once with alcohol. Dry at 130° C., and 
weigh as PbSQ,. 

Zinc. — The filtrate from the lead sulphide precipitate 
is boiled to expel hydrogen sulphide, treated while hot 
with a few drops of HNOs:, then rendered slightly am- 
*moniacal, and any precipitate which is formed is filtered 
off. The filtrate is then slightly acidified with acetic 
acid, heated to boiling and a stream of sulphuretted 
hydrogen passed in to precipitate the zinc. The latter 
is filtered and washed with water containing a small 
amount of acetic acid saturated with hydrogen sulphide, 
using a Gooch or alundum crucible for filtering. 

In filtering zinc sulphide, keep the crucible full of 
liquid or wash water until the precipitate is completely 
washed. Only then may the precipitate be allowed to 
drain free from wash water. 

The zinc sulphide is then dissolved in dilute hydro- 
chloric acid, the sulphuretted hydrogen expelled by boiling, 
and the zinc determined either volumetrically by the 
ferro-cyanide method or gravimetrically by precipitation 
with a slight excess of sodium carbonate, and ignition to 
oxid. 


ANALYSIS OF PAINT MATERIALS 335 


Calcium and Magnesium. — The filtrate from the zinc 
sulphide is evaporated to a small bulk and the calcium 
determined by precipitating hot from a slightly ammoni- 
acal solution with ammonium oxalate. Magnesium is 
determined as usual. 

Soluble Salis. —'To determine the presence of zinc sul- 
phate, 1 g. is digested with too c.c. of water, filtered, 
and the sulphate determined in the filtrate as usual, with 
barium chloride. 

Total Sulphates.— Dissolve 25 g. of sodium car- 
bonate in a beaker with 25 c.c. of water, add o.5 g. 
of the sample, boil gently for about ten minutes and 
allow to stand for several hours. Dilute with hot water, 
filter and wash until the filtrate is about 200 c.c. 

Render the filtrate slightly acid with hydrochloric, 
boil to expel carbon dioxid and precipitate the sulphate 
with a slight excess of barium chloride solution. 

Filter, wash and weigh as BaSO,. Calculate the lat- 
fersto-PbsO.. 


ZINC OxIbD 


Insoluble. — Dissolve 1 g. in hot dilute acetic acid. 
Filter, wash and weigh any insoluble residue. If the 
latter is very small in quantity, it should be deter- 
mined by dissolving a proportionately larger quantity of 
zinc oxid. 

Zinc. — Neutralize the filtrate with ammonia, then 
make faintly acid with acetic acid, dilute to 300 c.c., and 
precipitate with sulphuretted hydrogen. The solution 
should be kept hot during the precipitation, and should 
smell strongly of hydrogen sulphide at the end. Allow 
the precipitate to settle, decant through an alundum or 
Gooch crucible, keeping the crucible full of liquid during 
the filtration, wash the precipitate in the beaker with a 


336 CHEMISTRY AND TECHNOLOGY OF PAINTS 


hot 2 per cent acetic acid solution saturated with hydro- 
gen sulphide, finally transferring the zinc sulphide to the 
crucible and allowing the last wash water to drain com- 
pletely. The zinc sulphide is dissolved in dilute hydre- 
chloric acid and boiled to expel HS (test with lead acetate 
paper held in the escaping vapors from the beaker or 
flask to show the presence of hydrogen sulphide). 


Gravimetric Methods for Zinc. — (a) Precipitation as Phosphate 


The solution is rendered very faintly acid by almost 
completely neutralizing with ammonia, diluted to 150 c.c. 
and heated on the steam bath. Add to the solution on 
the steam bath about ten times as much di-ammo- 
nium phosphate! as zinc present. Heat for 15 minutes 
longer. The crystalline zinc ammonium phosphate is 
filtered through a Gooch or alundum crucible, washed 
with hot 1 per cent ammonium phosphate solution until 
free from chlorides, then with cold water and finally with 
so per cent alcohol. Dry at 120° C. for one hour and 
weigh as ZnNH.POk. 


(b) Precipitation as Carbonate 


The zinc chloride sclution is carefully neutralized in 
the cold with sodium carbonate solution until a precipi- 
tate begins to form. The solution is then heated to 
boiling, and precipitation completed by adding a slight 
excess of sodium carbonate (use phenolphthalein as indi- 
cator). Ammonium salts must not be present. Filter on 
a Gooch crucible, wash, ignite and weigh as ZnO. 

Volumetric Method. — Zinc is precipitated from hot 
somewhat acid solutions by the addition of potassium 
ferro-cyanide according to the following reaction: 


| 1 Dissolve in cold water and add dilute ammonia until faintly 
pink with phenolphthalein. 


ANALYSIS OF PAINT MATERIALS 


Go 
iON) 
~I 


3ZnCl, + 2KyFeCgNg = Zn3KyFe.(CN)» + 6KCI 


The end point is indicated by a solution of uranium ni- 
trate as outside indicator. A brown coloration is produced 
when a drop of the solution containing the excess of 
potassium ferrocyanide is ‘added to a drop of uranium 
nitrate solution on a spotting tile. 

Solutions Potassium Ferrocyanide.— Dissolve 21.6 g. 
of crystallized salt, KiFeC;N.«-3H.O in cold water and 
dilute to one liter. One c.c. of this solution is equivalent 
to about 0.005 g. zinc. 


Mrmiumeru trate, 6.98, eyo 25. 5% solution 
Ammonium chloride ..... 0.5... 10.0. per liter 


Standardization of Ferrocyanide. — Weigh out two or 
three portions of 0.2 to 0.25 g. of pure ignited zinc oxid. 
Dissolve in 1o c.c. of hydrochloric acid (1:2), add sodium 
carbonate solution or ammonia until a slight permanent 
precipitate is formed, redissolve the latter with one 
or two drops of hydrochloric acid, add 6 c.c. of concen- 
trated hydrochloric acid and to g. of ammonium chloride. 
Dilute to 180 c.c., heat to 70° C. and titrate with ferro- 
cyanide solution until the end point is reached. To 
- determine the end point rapidly divide the zinc solution 
into two unequal parts. Titrate the smaller part run- 
ning in the ferrocyanide solution 1 c.c. at a time. When 
an excess has been added pour in the rest of the zinc so- 
lution, run.in 1 c.c. less than the quantity of potassium 
ferrocyanide previously added, and finish the titration 
drop by drop. 

A blank must be deducted because of the excess of 
potassium ferrocyanide required to develop the brown 
coloration with uranium solution. 

To determine the allowance, add 6 c.c. of concentrated 
hydrochloric acid and 10 g. of ammonium chloride to 200 


338 CHEMISTRY AND TECHNOLOGY OF PAINTS 


c.c. of water in a beaker, heat to 7o° C., and add the 
ferrocyanide solution until the brown coloration is ob- 
tained with the outside indicator. The correction should 
be less than 0.5 c.c. Deduct this amount from all future 
titrations. 

Determination of Zinc.—'To determine zinc in the 
solution obtained by dissolving ZnS in hydrochloric acid 
and expelling hydrogen sulphide, neutralize with ammonia 
or sodium carbonate, reacidify slightly with dilute hydro- 
chloric acid, and proceed as outlined under “ Standardiza- 
tion of Ferrocyanide.’’ The presence of a small amount 
of lead does not interfere with the accuracy of the above 
method. 

Soluble Impurities. — Most zinc oxids are contami- 
nated with small quantities of cadmium and traces of iron, 
copper and lead. The cadmium! is best determined by 
dissolving a relatively large amount, 25 to 50 g., of zinc 
oxid in dilute sulphuric acid, filtering, diluting to 4oo c.c. 
and precipitating as sulphide in the presence of an 
excess of about 5 c.c. of concentrated sulphuric acid in too 
c.c. of solution. Filter, wash, redissolve in sulphuric acid 
and reprecipitate as sulphide. Dissolve into a crucible 
with as small an amount of sulphuric acid as possible. 
Evaporate cautiously and ignite to CdSQk,. 


LITHOPONE 
Metuop I 


Zinc Oxid. — Digest 1 g. with 100 ‘Gey Oherpeneaemn 
acetic acid at room temperature for one half hour. 
Filter, wash and weigh the insoluble. The loss in 
weight represents the zinc oxid present. 


1 For electrolytic method of determining Cadmium, see E. F. 
Smith’s “ Electro-Analysis.” 


ANALYSIS OF PAINT MATERIALS 339 


Insoluble and Total. Zinc. — Treat 1 g. in a 200 c.c. 
beaker with 10 c.c. of concentrated hydrochloric acid, 
mix, and add in small portions 1 g. of potassium chlorate 
(this should be carried out under a hood); evaporate on 
the steam bath to $ the volume. Dilute with hot water, 
add 5 c.c. of dilute sulphuric acid (1:10), boil, filter, and 
weigh the insoluble. The latter is barium sulphate. The 
zinc is determined in the filtrate by the methods outlined 
under “Zinc Oxid.”’ 


Metuop II 


Soluble Salis. — Treat 2 g. of lithopone with 100 
c.c. of hot water. Digest for a few minutes and filter 
on a Gooch crucible (test the filtrate for Ba, Zn and SQ,). 
Wash with hot water and finally once with alcohol. 
Dry the crucible in the air oven at 1too° C. and deter- 
mine loss in weight. The latter is equal to the per- 
centage of moisture present plus the water soluble 
salts. 

Zinc Oxid. — Digest for $ hour, without warming, a 1 
g. sample with too c.c. of 1 per cent acetic acid. Filter, 
wash, and determine the zinc in the filtrate gravimetrically 
or volumetrically, as outlined under “Zinc Oxid.” Cal- 
culate to ZnO. 

Zinc Sulphide. — Transfer the filter paper and residue 
to a beaker, treat with dilute hydrochloric acid (1:4) and 
boil to drive off H.S. Filter, wash with hot water, and 
determine the zinc in the filtrate by the usual methods. 
Report as Zns. 

Barium Sulphate. — The residue is dried, ignited, 
treated with a few drops of concentrated sulphuric acid 
in the crucible, again ignited and weighed as BaSOQu. 
Test the latter for clay or silica. Should any be present, 
treat the residue with hydrofluoric and sulphuric acids 


340 CHEMISTRY AND TECHNOLOGY OF PAINTS 


in a platinum crucible and evaporate to dryness. The 
loss in weight represents silica. 


ANALYSIS OF ‘TITANIUM WHITE? 


DETERMINATION OF BARIUM SULPHATE 


Weigh 4 gram sample into 250 c.c. Pyrex glass beaker; 
add 20 c.c. concentrated sulphuric acid and 7 or 8 grams 
sodium sulphate. Mix well and heat on hot plate until 
fumes of sulphuric anhydride are evolved and then heat 
directly over flame to boiling for five minutes or until 
solution is complete. Traces of silica, if any, remain as 
an insoluble residue. 

Cool, take up with too c.c. of water, boil and filter 
off barium sulphate and silica, washing with 5 per cent 
sulphuric acid to free residue from titanium. 


DETERMINATION OF TITANIUM 


The volumetric method used for determination of 
titanium is essentially that described by P. W. & E. B. 
Shimer; Proceedings of Eighth International Congress of 
Applied Chemistry; the method hereafter described differ- 
ing principally in the form of reductor and also in a few 
details of operation. 


REAGENTS 


Standard Ferric Ammonium Sulphate Solution. 

Dissolve 30 grams of ferric ammonium sulphate in 
300 c.c. water acidified with to c.c. of sulphuric acid; 
add potassium permanganate drop by drop as long as the 


‘ Courtesy Titanium Pigments Corp., 1923. 


ANALYSIS OF PAINT MATERIALS 341 


pink color disappears, to oxidize any ferrous to ferric 
iron; finally dilute the solution to one liter. 

Standardize this solution in terms of iron. The iron 
value multiplied by 1.4329 gives the value in titanic 
oxide (TiO.); and iron value multiplied by .86046 gives 
the value of the solution in terms of metallic titanium. 


INDICATOR 


Saturated solution of potassium thiocyanate. 


REDUCTOR 


As a reductor a 500 c.c. dispensing burette is used. The 
internal dimensions of the burette are 13 inches by 22 
inches. 

The reductor is charged with 1200 grams of 20 mesh 
amalgamated zinc, making a column about 12 inches high 
and having an interstice volume of about 135 c.c. This 
form of reductor is convenient, and when used as hereafter 
described is adapted to maintaining hot solutions, which 
is essential for complete reduction of the titanium. 

The reductor is connected to a liter flask for receiving 
the reduced titanium solution through a three-hole rubber 
stopper, which carries also an inlet tube for carbon dioxide 
supply, and outlet tube for connecting with the suction 
pump. 

The reductor is prepared for use by first passing through 
it a little hot dilute sulphuric acid followed by hot water, 
finally leaving sufficient hot water in the reductor to fill 
to the upper level of the zinc. 

The hot filtrate from the barium sulphate determination 
is now introduced; about 100 c.c. of water being drawn 
from the reductor into the original beaker to bring the 


342 CHEMISTRY AND TECHNOLOGY OF PAINTS 


solution to about the upper level of the zinc. The water 
thus removed will not contain any titanium if the operation 
has been conducted as described, but it serves as a safe- 
guard and is also convenient to acidify this water with 
to c.c. sulphuric acid and reserve it on the hot plate to 
be used as an acid wash after the reduction of the sample 
solution. 

The titanium solution is allowed to remain in the re- 
ductor for to minutes. 7 

While the solution is being reduced, the receiving flask 
is connected to the reductor and the air completely dis- 
placed by carbon dioxide, conveniently drawn from a 
cylinder of the liquefied gas. 

When the reduction is complete the receiving flask is 
connected with the suction pump, and while still con- 
tinuing the flow of carbon dioxide the reduced solution 
is drawn out, followed by the reserved acid wash and then 
three or four 100 c.c. washes with hot water. The dis- 
placement of the sample solution and washing of the zinc 
is so regulated by means of the stopcock that the reductor 
is always filled with solution or water to the upper level of 
the zinc. 3 

When the washing is complete, gradually release the 
suction to prevent air being drawn back into the receiving 
flask. 

Disconnect the flask, add 5 c.c. of potassium thio- 
cyanate solution as indicator and titrate immediately with 
standard ferric ammonium sulphate solution, adding the 
solution rapidly until a brownish color is produced, which 
will remain for at least one minute. 

The method is also well adapted for determining 
titanium in other titanium products; suitable means being 
employed for bringing the titanium into sulphuric acid 
solution. | 


ANALYSIS OF PAINT MATERIALS 343 


Constants for Titanium White: Titanium Dioxid (TiO.) 
— 25 per cent, Barium Sulphate (BaSO,) 75 per cent, specific 
gravity, 4.3. 
RED LEAD AND ORANGE MINERAL 


Lead Peroxid (Method I). — Dissolve 0.5 g. in a beaker 
with 30 c.c. of 2N nitric acid, heat to boiling to complete 
solution. Add 25 c.c. N/5 oxalic acid, accurately meas- 
ured from a pipette or burette, boil and titrate hot 
with KMnQ,. 

A blank containing the same quantities of nitric acid 
and oxalic acid is also titrated against the permanganate. 
The difference between the two titrations represents the 
-amount of PbO, reduced by oxalic acid. 


Pb30, + 4HNO;3 = 2Pb (NO3)2 + H.O + H3PbO3 
PbO. + HeC.0O4 = PbO + H2O+ 2CO. 


Lead Peroxid (Method IT).— Mix together in a small 
beaker 1.2 g. of potassium iodide, 15 g. sodium acetate 
and 5 c.c. of 50 per cent acetic acid. Weigh off 0.5 g. of 
red lead in a 150 c.c. Erlenmeyer flask and add the above 
mixture to it. Stir until the lead is completely dis- 
solved. Dilute to 25 c.c., and titrate with N/r1o sodium 
thiosulphate, using starch as indicator. 

A little red lead, especially when it is not very fine in 
texture, at first resists solution in the potassium iodide 
mixture, but dissolves, on mixing, toward the end of the 
titration. Proceed with the titration as soon as the lead is 
in solution, so as to avoid loss of iodine by volatilization. 

The reaction involved in the above method is 


PbO» + AHI = PbI, + 2H.O + I, 


The lead peroxid is reduced in the presence of an 
excess of sodium acetate when treated with potassium 
iodide in acetic acid solution. 


344 CHEMISTRY AND TECHNOLOGY OF PAINTS 


ANALYSIS OF IRON OxIDS 


Moisture. — Heat. 2 g. in*the air oven atmos Gaon 
two hours. 

Loss on Ignition. — Ignite 1 g. in a porcelain crucible 
to a red heat. The loss in weight consists of hygros- 
copic moisture, water of combination, sometimes organic 
matter, and carbon dioxid due to the presence of car- 
bonates. | 

* Insoluble. — Digest 1 g. of the oxid with 20 c.c. of 
hydrochloric acid (1:1) on the hot plate for 15 minutes. 
Filter, wash and weigh the insoluble residue. The 
latter may be examined to determine the presence of 
barytes, clay or silica. 

Iron Oxid.— Weigh off from 0.3 to 1.0 g., depend- 
ing upon the amount of iron oxid present, treat with 
20 c.c. of hydrochloric acid (1:1) on the hot plate until 
the residue is white, and while hot reduce with a strongly 
acid stannous chloride solution until the iron solution 
is colorless, using only one or two drops in excess. Wash 
down the sides of the beaker and the cover glass with a 
little water, add all at once ro c.c. of a saturated solution 
of mercury bichloride, stir, and wash the whole into a 
large beaker containing 400 c.c. of cold distilled water to 
which has been added to c.c. of preventive solution. 
Titrate with N/1o potassium permanganate to a faint 
pink. 

In the case of magnetic oxids and certain purple 
oxids, solution is facilitated by the addition of 1 to 3 c.c. 
of a 25 per cent stannous chloride solution. Should the 
residue after digestion on the hot plate still show greenish 
or black, filter, wash, and determine the iron in the soluble 
portion as outlined below. 


ANALYSIS OF PAINT. MATERIALS 345 


To determine iron in the insoluble portion, fuse in a 
porcelain crucible with five times its weight of potassium 
bisulphate for about } hour. Cool, dissolve in water and 
filter. Determine iron in the filtrate after reduction as 
outlined below. 

Stannous Chloride Solution. — Dissolve 50 g. of stan- 
nous chloride in too c.c. of hydrochloric acid and dilute 
to 1000 c.c. To preserve the solution, always keep a 
few pieces of metallic tin at the bottom of the bottle. 


PREVENTIVE SOLUTION: 


Crystallized Manganese Sulphate....... 67g 

NTIS Os CCNA ak ee 500 C.C 
Syrupy Phosphoric Acid (Sp. Gr. 1.7). ..138 c.c. 
Cencentiated sulphuric Acid)... .....130 C.c. 


Dissolve in the order named and dilute to 1 liter. 


ANALYSIS OF UMBERS AND SIENNAS 


To 0.5 to 1.0 g., depending upon the amount of iron 
oxid present, in a casserole, add 20 c.c. of hydrochloric 
acid (1:1) and 0.35 g. potassium chloride (or 0.25 g. 
ammonium chloride), and evaporate to dryness on the 
steam bath. Heat for 1o minutes longer to expel hydro- 
chloric acid. Dissolve the soluble salts in about 25 c.c. 
of hot water, filter and wash the insoluble residue. The 
latter is dried, ignited and weighed, and reported as 
insoluble or silicious matter. (When necessary analyze 
this separately as indicated under “Analysis of Silica, 
Asbestine or Clay’’.) 

To the filtrate, heated almost to boiling, there is 
added 3.0 g. of sodium acetate for every 0.3 g. of iron 
in solution, and 4oo c.c. of boiling water. Heat to 
incipient boiling. By this means the iron is quantita- 
tively precipitated as a basic acetate, while manganese 


346 CHEMISTRY AND TECHNOLOGY OF PAINTS 


and other divalent metals of the group stay in solution. 
The precipitate is allowed to settle, the solution decanted 
off and filtered; the precipitate is washed several times 
with hot water, dissolved in a small amount of hot dilute 
hydrochloric acid, and either precipitated with ammonia 
or determined volumetrically as under “Analysis of Iron 
Oxids.” The filtrate is evaporated to about half its 
volume, treated with an excess of bromine water, and 
then boiled until the precipitated manganese dioxid be- 
comes floccular. The precipitate is then filtered off, 
washed, and ignited to Mn;Q,. 

Calcium and magnesium are determined in the fil- 
trate in the usual way. When appreciable quantities of 
these two elements are present, it is best to separate the 
manganese by precipitation as sulphide. 

To determine manganese as sulphide, heat the neutral 
solution to boiling, add an excess of ammonia and am- 
monium sulphide, and continue the boiling until the man- 
ganese sulphide. becomes a dirty green. Decant through 
a Gooch crucible, using gentle suction, keeping the cru- 
cible filled all the time. Wash the precipitate twice by — 
decantation with 5 per cent ammonium nitrate solution con- 
taining a little ammonium sulphide, add to the crucible 
and filter, allowing the crucible to drain. The filtrate 
is acidified with dilute acetic acid boiled to expel hydro- 
gen sulphide, and the calcium and magnesium deter- 
mined as usual. The precipitated manganese sulphide 
is dissolved in a little hot dilute hydrochloric acid, 
evaporated to expel hydrogen sulphide, and precipitated 
as carbonate or phosphate. In the first case the man- 
ganese is ignited and weighed as Mn;Qk. 

Colorimetric Determination of Manganese.! — Dissolve 


' Treadwell, Volume II, pages 127, 128. Marshall, Chem. News, 
83, 76 (1904). Walters, Chem. News 84/239 (1904). 


ANALYSIS. OF PAINT MATERIALS 347 


0.5 g. of umber or sienna in about ro c.c. of hydrochloric 
acid (1:1) in a casserole, add an excess of nitric acid and 
evaporate to dryness to drive off the hydrochloric acid. 
Cool, add 20 c.c. of cold nitric acid (specific gravity 1.2) 
filter and wash with the least quantity of cold water into 
a i100 c.c. graduated flask. Make up to the mark. 
Remove to c.c. by means of a pipette to a graduated 
test tube, add io c.c. of silver nitrate! solution, and 2.5 
c.c. of ammonium persulphate? solution, mix, and place the 
tubes in water at 80 to 9o° C. until bubbles of gas arise, 
and remain at the top for a few seconds. Cool the test 
tubes and compare against standard tubes made with 
known amounts of manganese. 


MERCURY VERMILION 


This pigment is very expensive and therefore quite 
often adulterated. The possible adulterants are organic 
lakes, orange lead chromes, red lead, and iron oxids, as 
well as barytes, silica or clay. 

Its high specific gravity (8.2) and its insolubility in 
alkalies, and in any one acid, distinguish it from all other 
pigments of like color. 

A pure vermilion can be volatilized completely on 
heating, leaving no residue. On account of the ex- 
tremely toxic properties of mercury vapors, such volatili- 
zation should be carried out in a hood having a good 
draft. 

Barytes, Silica or Clay. — Dissolve 2 g. in aqua regia, 
or hydrochloric acid with a little potassium chlorate, and 
after evaporating to dryness take up with boiling water 
and a little hydrochloric acid. Filter and weigh the 
residue. 


1 7.38 g-AgnOs in 1000 c.c. of water, 
2 20% solution. 


348 CHEMISTRY AND TECHNOLOGY OF PAINTS 


Lead. — Evaporate the filtrate from the above with an 
excess of dilute sulphuric acid to SO; fumes, and deter- 
mine lead as PbSO,. (Calcium must be absent.) 

Free mercury, free sulphur and iron may be identified 
by dissolving the mercury vermilion in potassium mono- 
‘sulphide (1:1), in which it dissolves readily. The solu- 
tion is colorless after the iron sulphide has settled out. 
Free mercury settles to the bottom of the dish as a gray 
sediment. 

Free sulphur is recognized by the yellow coloration of 
the solution. It may also be detected in the usual way by 
digesting with potassium hydroxid or extraction with 
carbon disulphide (if present in crystalline form). The 
quantitative determination is carried out by extracting with 
soda solution and oxidation to sulphate. 

For separating foreign adulterations such as barytes, 
clay, litharge, chrome red, brick dust, etc., potassium sul- 
phide may be used to advantage. After filtering, wash 
with dilute KOH solution and not with water, otherwise 
the Brunner’s salt decomposes with separation of black HgS. 

The coal tar colors are identified by extraction with 
alcohol; carmines by the drop test with ammonia on filter 
paper. 

For detecting arsenic sulphide, boil with caustic soda, 
acidify with hydrochloric acid and introduce H.S gas into 
the solution. 


ANALYSIS OF CHROME YELLOWS AND ORANGES 


Organic Matter. —'Test with alcohol to determine pres- 
ence of organic coloring matter. 

Insoluble. — Boil 1 g. for about 5 minutes with 20 c.c. 
of concentrated hydrochloric acid, adding 1 or 2 c.c. of 
alcohol drop by drop. Dilute with about roo c.c. of 
boiling water. Boil a few minutes longer. Filter, wash 


ANALYSIS OF PAINT MATERIALS 349 


with boiling water, and weigh the insoluble. Test the 
latter for barium sulphate, clay or silica. 

Lead. — Neutralize the filtrate with ammonia until a 
slight permanent precipitate appears. Reacidify shghtly, 
using an excess of not more than 1.5 ¢c.c. of concentrated 
hydrochloric acid in too c.c. of solution. Dilute to 200 
c.c. Precipitate the lead with hydrogen sulphide. Fil- 
ter, wash with H.S water, dissolve the PbS in hot dilute 
nitric acid, boil to expel H.S, add to c.c. of dilute H.SO, 
(1:1), evaporate to fumes of SO; and determine lead 
gravimetrically or volumetrically as outlined under 
“White Lead.” 

Chromium. — Evaporate the alcoholic filtrate from the 
PbSO, almost to dryness and mix with the filtrate from 
PbS. The chromium is determined by precipitating hot 
with a slight excess of ammonia. Filter, wash, ignite and 
weigh as Cr.Qs. 

Zinc. — The filtrate from chromium hydroxid is ana- 
lyzed for zinc by precipitating with hydrogen sulphide. 
Bee inc Oxid:” 


CHROME GREENS 


Preliminary Test. — Determine the presence of organic 
coloring matter by extraction with alcohol. 

Insoluble. —In a small evaporating dish heat 1 g. 
sample at as low a temperature as possible until the blue 
color is completely discharged. ‘Transfer to a beaker, and 
boil with 20 c.c. of concentrated hydrochloric acid and a 
little alcohol to dissolve the soluble portion. Dilute with 
hot water, boil, filter, wash, and weigh the insoluble por- 
tion. Examine the latter for silica, clay or barytes. 

Lead. — Determine in the filtrate after neutralizing 
with ammonia and reacidifying slightly with hydro- 
chloric acid as under “‘Chrome Yellows.”’ 


350 CHEMISTRY-AND TECHNOLOGY: OF PAINGS 


Chromium, Iron and Aluminium.— Boil the filtrate from 
the lead sulphide to expel hydrogen sulphide, add a few 
drops of nitric acid and about 2 g. of ammonium chloride. 
Heat to boiling, and precipitate iron, aluminium, and 
chromium as hydroxids with ammonia in slight excess. 
Filter and wash the precipitates. Dissolve the mixed 
hydroxids in a small amount of hot dilute hydrochloric 
acid and dilute to r50c.c. Heat to boiling and treat with 
an excess of sodium hydroxid, and bromine water. 
Filter and wash. Redissolve the ferric hydroxid in 
dilute hydrochloric acid, and determine iron by the usual 
methods. 

The filtrate is acidified faintly with hydrochloric acid 
and aluminium hydroxid precipitated with a slight excess 
of ammonia. 

The filtrate from aluminium hydroxid is carefully 
acidified with acetic acid, and the chromium precipitated 
by the addition of barium acetate to the hot solution. 
Allow to stand for some time, and filter through a Gooch 
or alundum crucible (using gentle suction). Wash with 
alcohol, and dry in hot closet. Finally ignite at a dull 
red heat by suspending the crucible inside a larger por- 
celain crucible by means of an asbestos ring. If desired 
the chromium present as alkali chromate may be reduced 
to chromic salt by evaporating with hydrochloric acid 
and alcohol. The chromium may then be precipitated 
by ammonia and weighed after ignition as Cr.O3. 

Calcium and Magnesium. — Determine as usual in the 
filtrate from iron, aluminium and chromium hydroxids. 

Sulphates. — Treat 1 g. as mentioned in the second 
paragraph of this section. Determine sulphates as under 
“Zinc Lead.” d 

Nitrogen. — Determine by the Kjeldahl-Gunning 
method. 


ANALYSIS OF PAINT MATERIALS 351 


PRUSSIAN BLUE 


Hygroscopic Moisture. — Determine on a 1 g. sample 
by heating for 2 hours at 1o5° C. 

Water of Composition. — Determine by difference after 
the other constituents have been obtained. 

Ferrocyanic Acid.1— Treat 0.5 g. with to c.c. of nor- 
mal potassium hydroxid solution in a flask. Boil for 5 
Mmimuress diuute with so c.c.-of hot water, filter, and 
wash the ferric hydroxid. 

The filtrate containing a solution of potassium fer- 
rocyanide is slightly acidified with sulphuric acid, 2 to 3 
g. of ammonium persulphate are added, and the liquid 
boiled from 20 to 30 minutes. Any blue color which 
persists is removed by the addition of hydrochloric acid 
and a little more persulphate. 

The iron is precipitated with ammonia by the usual 
method gravimetrically or volumetrically. Calculate as 
FeC,Ne. 

Cyanogen. —If desired, the total nitrogen in Prussian 
blue may be determined by the Kjeldahl-Gunning method 
as outlined in Bulletin 107, Bureau of Chemistry, U. S. 
Dept. of Agriculture. 

To determine the amount of Prussian blue, multiply 
the total iron content by 3.03 or nitrogen content by 4.4. 
The results thus obtained are fairly approximate. They 
are not exact since the composition of Prussian blue is 
variable. The pure Prussian blue should contain about 
20 per cent of nitrogen and 30 per cent of iron, and less 
than 7 per cent of moisture. The sulphuric acid used in 
determining the nitrogen by the Kjeldahl-Gunning method 
should not be blackened due to the presence of organic 
adulterants. 

Lwiset eal O04, «40.1020; 


352 CHEMISTRY AND TECHNOLOGY OF PAINTS 


fron. — To determine the total iron in Prussian blue, 
ignite 1 g. gently until the blue color is completely dis- 
charged. Dissolve the residue in to c.c. of hydrochloric 
acid (1:1), filter, make up to roo c.c. in a graduated flask. 
Determine Fe,O; in 50 c.c. in this solution (calculate to 
metallic iron). 

In the other 50 c.c. of the filtrate determine Fe,O; + 
Al,O; by the usual methods. Calculate Al,O; by difference. 
Report as metallic aluminium. 

Calcium.— Determine as usual in the filtrate from 
Fe,O; + Al.Os. 

Alkali Metals. — Determine by the usual methods. 


ANALYSIS OF ULTRAMARINE 


I 


The ultramarine is finely powdered and dried at 100°. 
2 to 10 g. are weighed off, digested with water, filtered, - 
the filtrate diluted to 500 c.c., and 100 c.c. taken for each 
of the following determinations. 

(a) Na2S.0;— determine with iodine solution and 
starch. Calculate to Na.S,O; + Ag. ; 

(b) NasSO,— determine by precipitating with barium 
chloride in acid solution. 

(c) NaCl — determine by precipitating with AgNO; 
(NaCl is rarely present in ultramarine). 

to to 20 grams of ultramarine are washed two or three 
times by decantation (to obtain a clear filtrate, alcohol is 
added). Evaporate almost to dryness with a dilute solu- 
tion of sodium sulphite! on the water bath. Wash until 
a test of the ultramarine moistened with water and fil- 
tered gives no trace of turbidity with barium chloride. 


' In order to remove free S, for CS, extracts only 40 to 60% 
of the same. 


ANALYSIS OF PAINT MATERIALS 353 


(he ultramarine dried at 130 to 140° is again powdered 
and placed hot into a glass stoppered flask. 


II 


Estimation of silicic acid, silica, clay and total sulphur. 

1 g. of the dried substance is weighed into a porcelain 
dish, stirred up with water and treated with 1 to 2 c.c. of 
bromine. If it is partially dissolved (as shown by the yellow 
coloration of the liquid) 15 to 20 c.c. of nitric acid are added 
and the whole evaporated to dryness on the water bath. 

Take up with water, add 20 c.c. of hydrochloric acid 
and evaporate again (to remove nitric acid which would 
increase the BaSO, precipitate, and to render silicic acid 
insoluble). Treat with hydrochloric acid, digest warm 
for a few hours, dilute with water and filter. On the 
filter are left silicic acid and sand. 

To determine total sulphur, the filtrate is heated to 
boiling and precipitated with barium chloride. 


ISH 


Estimation of alumina and of soda. 

t g. of ultramarine, washed and dried as in number 
I, is carefully mixed with water and treated with an ex- 
cess of hydrochloric acid. After standing for a while it 
is heated until the solution settles clear. It is then fil- 
tered, leaving sulphur, sand and silicic acid undissolved. 
The residue is weighed after ignition. The filtrate is 
evaporated to dryness, the residue moistened with water 
and hydrocloric acid and again dried. Take up with 
hydrochloric acid, dilute with water after standing for 
some time and filter. On the filter is left silicic acid, 
which, added to the residue obtained in the first filtra- 
tion, gives the content of total silicic acid and sand. The 
filtrate is evaporated to dryness to remove excess hydro- 


354 CHEMISTRY AND TECHNOLOGY OF PAINTS 


chloric acid. The residue is dissolved in water, precipi- 
tated with ammonia and the whole thoroughly dried in 
the water bath. (This facilitates complete washing of 
the alumina.) 

Take up the residue with hot water, add a few drops 
of ammonia, heat and filter. Alumina on the filter is 
determined and weighed. 

For determining soda, the filtrate is treated with sul- 
phuric acid and a little fuming nitric acid and evaporated 
to dryness. The residue is strongly ignited and the 
Na.SO, calculated to Na. | 3 


BLACK PIGMENTS 


(Carbon Black, Lampblack, Vine Black, Bone Black) 


Moisture. — Determine on a 2 g. sample by heating 
for two hours at 105° C. 

Volatile. — Heat for to minutes over a Bunsen flame - 
in a well-covered porcelain crucible. 

Ash. — Determine on a 1 g. sample, ignite over a 
Bunsen burner with free access of air. When the ash is 
large in quantity, cool, moisten with a solution of ammo- 
nium carbonate and ignite again gently. 

Soluble and Insoluble Ash.— Treat the ash obtained 
by the above procedure with 5 to to c.c. of dilute hydro- 
chloric acid, heat, filter, wash and weigh the insoluble 
portion. Calculate the percentage of acid-soluble ash 
from the total ash and the acid-insoluble ash. 

Certain blacks are sometimes adulterated with Prus- 
sian blue. To detect the latter, boil with dilute caustic 
soda, filter, acidify the filtrate with dilute hydrochloric 
acid, and add a mixture of ferric chloride and ferrous 
sulphate. The formation of a blue precipitate indicates 
the presence of Prussian blue. 


ANALYSIS OF PAINT MATERIALS 355 


GRAPHITE 


Heat 1 g. of the finely powdered graphite to a dull 
red heat and calculate the loss in weight as water. The 
dried substance is intimately mixed with 3 g. of a mixture 
of equivalent parts of K,CO; and Na,CO; and placed in a 
crucible. 1 g. of KOH or NaOH is sprinkled over the 
surface of this mixture and the whole heated slowly to 
redness. ‘The mass fuses, swells and forms a crust on top, 
which must be broken with a stout platinum wire. 

After fusing for one half hour, the melt is cooled, 
heated with water for ~ hour almost to boiling, filtered, 
washed well and the liquids set aside. The insoluble is 
dried, placed in a dish, the filter ash added and about 3 g. 
of HCl (specific gravity 1.18) poured in. After several 
minutes a slight gelatinization sets in due to the decom- 
position of the small residue of alkali silicate. The addi- 
tion of a little more hydrochloric acid brings the silicic 
acid into solution. After digestion for one hour, dilute 
with water, filter and wash out. The residue on the fil- 
ter is pure carbon, which, after drying and gentle ignition, 
is welghed. The acid filtrate is united with the alkaline 
one obtained above, more HCl added until weakly acid, 
evaporated to dryness, and silicic acid, alumina and iron 
oxid determined as usual. 


BLANC FIXE 


Water Soluble Salts. — Owing to the variety of methods 
employed in the technical production of blanc fixe, a 
preliminary qualitative examination of the material is 
always essential before proceeding with the quantitative 
analysis. 

Digest about 5 g. with 150 c.c. of hot water and 
filter. Examine the filtrate to detect the presence of 


356 CHEMISTRY AND TECHNOLOGY OF PAINTS 


water so'uble salts. Determine the amount of water 
soluble salts, by difference, on a 1 g. sample. 

Acid Soluble.— Digest 1 g. of blanc fixe with hot water, 
wash by decantation and filter, keeping as much of the 
residue as possible in the beaker. Discard the filtrate 
and treat the residue in the beaker with about 25 c.c. of 
hot dilute HCl (1:3); filter through the filter paper used 
above, wash and ignite. Add 1 drop of nitric and 2 drops 
of sulphuric acid, evaporate, ignite again and weigh. Cal- 
culate % acid soluble from loss in weight, % water soluble 
and % moisture. | | 

BaSO,.— Proceed as outlined below under barytes 
(fusion in platinum with Na.CO;) to determine barium 
sulphate and silica (Page 359). 

Iron. — Determine colorimetrically. 

Silica. —'To determine qualitatively ' whether a sample 
of blanc fixe is free from silica or clay, heat about 0.5 g. 
with ro to 15 c.c. of concentrated sulphuric acid. A pure 
blanc fixe or barytes dissolves completely. Silicious matter 
remains undissolved. Determine the amount of silicious 
matter on a 1. g. sample by evaporating with a few c.c. 
of hydrofluoric acid and several drops of sulphuric acid. 


ANALYSIS OF WHITING 


Carbon Dioxid. — Determined as outlined under “ White 


Lead.” 
Calcium. — Determined by the usual methods. 


GYPSUM OR CALCIUM SULPHATE 


Calcium and Sulphates. — Determine by the usual 


methods. 
Moisture. — Dry 2 g. in a vacuum dessicator over 


sulphuric acid to constant weight. 
1 Method developed in the laboratory of Toch Brothers. 


ANALYSIS OF PAINT MATERIALS 357 


Combined H,O and Moisture. — Heat 1 g. in a covered 
porcelain crucible on an asbestos plate for 15 minutes, 
then heat the bottom of the crucible to dull redness for 
Io minutes over a Bunsen burner, remove the cover and 
heat for 30 minutes at a slightly lower temperature. 
Cool and weigh rapidly. 


SILICA, ASBESTINE, CLAY BARYTES 


Hygroscopic Moisture. — Determine on a 2 g. sample 
by heating for 1 hour at 1os° C. 

Loss on Ignition. — Determine on a 1 g. sample. This 
is largely water of composition, unless carbonates are 
present. 

Complete Analysis. — Mix 0.5 g. in a platinum crucible 
intimately with about 5 g. of anhydrous sodium car- 
bonate. Add a thin layer of the latter on top, cover 
the crucible and heat gently over a Tirrill or Tech burner 
for a short time. Raise the temperature gradually to 
the full heat of the burner. Finally heat for a short 
time over the blast lamp. Allow to cool, then heat the 
lower part of the crucible to dull redness, and cool again. 
Add a little water, heat carefully to boiling and the melt 
will readily separate trom the crucible. Place the melt 
in an evaporating dish; wash the crucible with a little 
hot water, and add to the dish. If barytes, or blanc fixe 
is present, the melt is digested with hot water until 
completely disintegrated, the barium carbonate is fil- 
tered off and washed, and the barium determined as 
outlined under barium carbonate. The filtrate is then 
treated in a large covered beaker with concentrated 
hydrochloric acid. After a certain amount of acid has 
been added, the silicic acid separates out as a gelatinous 
mass, which has to be broken up in order to obtain inti- 
mate admixture with the acid. After an excess of acid 


358 CHEMISTRY AND TECHNOLOGY: OF “PAINTS 


has been added, the solution is heated to boiling, trans- 
ferred to a porcelain or platinum dish and evaporated to 
dryness. 

It is essential that dehydration of the silica be carried 
out twice! at the temperature of the steam bath and that 
the insoluble silica be filtered off before evaporating the 
second time. 

Filter, wash, combine the insoluble residues from the 
two dehydrations, ignite in a platinum crucible and weigh. 
Drive off SiO. with a few c.c. of HF and several drops of 
H.SO,. Ignite and reweigh.- The loss in weight is silica. 

Iron and Aluminium Oxids.— Treat the filtrate from 
the silicic acid with a few drops of concentrated nitric 
acid and to to 20 c.c. of a cold saturated solution of 
ammonium chloride. Heat to boiling and _ precipitate 
with a slight excess of ammonia. Allow the precipitate 
to settle, filter off the clear liquid and wash twice by 
decantation. with hot water. Redissolve the ferric and 
aluminium hydroxids by running hot dilute hydrochloric 
acid through the filter paper into the beaker containing 
the major portion of the precipitate. Reprecipitate with 
ammonia, as before, filter, wash and ignite wet in the 
platinum crucible containing the residue obtained after 
S10. was volatilized with HF and H,SO, Weigh as 
Fe,O; + Al.Os. 

For the determination of iron in the mixed oxids, see 
Treadwell and Hall, Vol. II, p. roo. 

Calcium. — Evaporate the filtrates from the ferric and 
aluminium hydroxids to a small volume. Heat to boil- 
ing and precipitate with a boiling solution of ammonium 
oxalate. Allow to stand for several hours. Filter and 
wash. Puncture the filter paper with a glass rod, wash the 
precipitate into a beaker with a stream of water from the 

' Hillebrand, “Analysis of Silicate and Carbonate Rocks.” 


ANALYSIS OF PAINT MATERIALS 359 


wash bottle, and pass 20 c.c. of hot dilute sulphuric acid 
(1:1) over and through the filter paper. Heat to go° C. 
and titrate with N/1o KMnOQ,. 

Magnesium. — Evaporate the filtrate from the calclum 
oxalate to dryness, and ignite in a porcelain dish. Moisten 
the residue with a little concentrated hydrochloric acid 
and dissolve in hot water. Filter and determine mag- 
nesium in the filtrate. Heat to boiling and treat with an 
excess of sodium or ammonium phosphate. Add an 
amount of ro per cent ammonia equal to § of the volume of 
solution. Allow to cool and set aside for a few hours. 
Filter through an alundum crucible, wash with 2.5 per cent 
ammonia, dry, ignite slowly at first and finally strongly 
until the precipitate is white. Weigh as Mg.P.O,. 

Alkalies. —See J. Lawrence Smith (Bulletin 422, U. 
S. Geologic Survey). 


BARYTES 


Make a preliminary test for lead compounds. In 
the absence of the latter weigh off 1 g. sample and mix 
with 5 g. anhydrous sodium carbonate in a platinum 
crucible. Fuse over the blast lamp for a half hour, occa- 
sionally imparting a rotary motion to the crucible to 
insure thorough reaction. Allow to cool, then heat the 
lower part of the crucible to dull redness, and cool again. 
Add a little water, bring carefully to boil, and the melt 
will readily separate from the crucible. Place in an 
evaporating dish, add too c.c. of water, and digest on 
the steam bath until completely disintegrated. Filter 
and wash the insoluble residue (BaCO;) until free from 
soluble salts. Dissolve the BaCO; with 25 c.c. of hydro- 
chloric acid (1:3), catching the filtrate and passing it 
through the filter to insure complete soluticn of the 
barium carbonate. Boil to expel carbon dioxid, neu- 


360 CHEMISTRY AND TECHNOLOGY OF PAINTS 


tralize the filtrate with ammonia, reacidify with a few 
drops of hydrochloric acid, heat to boiling, and precipi- 
tate with dilute sulphuric acid. Filter and wash on a 
Gooch crucible, dry at 130° C. and report as BaSQu. 

In the presence of lead, first extract the barytes with 
hot concentrated ammonium acetate solution before 
proceeding with the sodium carbonate fusion, since the 
presence of metallic lead in the fusion will ruin the 
platinum crucible. 

Iron. — Determine colorimetrically. 

Clay and Silica. — Acidify the filtrate from the barium 
carbonate with hydrochloric acid, evaporate to dryness 
on the steam bath, heat for 20 minutes longer on the 
steam bath, and extract with hot water and a little 
hydrochloric acid. Filter, wash and weigh the insoluble 
SiO.. Determine alumina in the filtrate from SiO, as 
usual. See also determination of silica in blanc fixe 
(p. 356). 

In reporting the presence of silica and alumina, it 
must be remembered that the reagents used in the above 
determination, sodium carbonate and ammonia, almost 
always contain appreciable quantities of silica and alu- 
mina. Especially is this true of aqua ammonia, except 
when kept in bottles lined with ceresin or paraffin wax. 


ANALYSIS OF BARIUM CARBONATE 


Water Soluble Salts. — Determine by difference in a 1 
g. sample, treat with hot water, filter, wash, and weigh 
the insoluble. 

Insoluble. — Dissolve about to g. in dilute hydro- 
cnloric acid. Heat to boiling, filter, wash and weigh 
the insoluble residue. The latter is generally silicious, 
but should be examined to determine the presence of 
barium. 


ANALYSIS OF PAINT MATERIALS 261 


Barium. — Dissolve o.5 g. in dilute hydrochloric acid, 
neutralize with ammonia, then reacidify faintly with 
hydrochloric acid. Dilute to too c.c., heat to boiling, 
and precipitate with hot dilute sulphuric acid. Filter on 
a Gooch crucible, wash, and dry at 130° C. Calculate 
BaSO, to BaCO;. For the separation of barium, cal- 
cium, and strontium from each other, see Treadwell and 
ane Chem:,; Vol. 11, p. 70. 

Carbon Dioxid.— Determine by evolution as outlined 
under ‘White Lead.” 

Tyvon.— Treat 2 g. in a beaker with 15 c.c. of water 
and sufficient nitric acid to dissolve the barium carbonate. 
Boil for several minutes to expel carbon dioxid and to 
convert all the iron to the ferric state. Filter and 
wash the residue. Cool the filtrate, neutralize with 
ammonia and acidify faintly with nitric acid. 

Wash the contents of the beaker into a 100 c.c. 
Nessler cylinder, add 15 c.c. of dilute ammonium thio- 
cyanate (1:20) and dilute to the mark. The depth of the 
blood red color developed is a measure of the amount of 
iron present. Compare with a blank made as follows: 

Prepare a standard solution of ferric ammonium sul- 
phate by dissolving 0.7022 g. of ferrous ammonium sul- 
phate in water. Acidify with sulphuric acid, heat to 
boiling and oxidize the iron by the addition of a solu- 
tion of potassium permanganate. Only the faintest 
excess of permanganate should be added. The faint pink 
tinge due to the latter soon disappears. The solution is 
cooled and diluted to 1 liter. One c.c. of this solution 
is equivalent to o.ooo1 g. of iron. 

Into a too c.c. Nessler cylinder add about the same 
amount of nitric acid as was used to dissolve the barium 


1 Modified Thompson & Schaeffer method. J. Ind. Eng. Chem. 
1912, 659. 


362 CHEMISTRY AND TECHNOLOGY OF PAINTS 


carbonate, and 15 c.c. of ammonium thiocyanate solution. 
Dilute to too c.c. and add the standard ferric ammonium 
sulphate solution, drop by drop, until the color exactly 
matches that developed in the sample being tested. 
One c.c. of the solution is equivalent to o.o1 per cent 
iron when a 1. g. sample is used. Not more than 
2 or 3 c.c. of the standard should be required to equal 
the color; otherwise, the color becomes too deep for 
comparison. 

Sulphur.— For colorimetric determination see Tread- 
well & Hall, Vol. II, pages 354-7. 

Chlorine. — Determine in the water soluble portion 
(acidified with nitric acid) by precipitating hot in the 
presence of a slight excess of silver nitrate, filter on a 
Gooch or alundum crucible, wash, and weigh the insoluble 
AgCl after drying at 130° C. 


ANALYSIS OF MIXED WHITE PAINTS 
I... By: useof Aceng Ae 

Treat 1 g. of the mixed white pigment with 22 c.c. of 
water and to c.c. of glacial acetic acid. Boil, filter, and 
wash with water. The filtrate is heated to boiling, and 
precipitated with hydrogen sulphide. Filter off the lead 
and zinc sulphides, dissolve in hot dilute nitric acid, and 
determine lead and zinc as usual. Calculate the lead to 
white lead, and zinc to oxid. The filtrate from lead and 
zinc sulphides is tested for Ba, Ca, and Mg. Determine 
and calculate to carbonates. 

To the residue from the acetic acid treatment add 
10 c.c. of water, ro c.c. of strong hydrochloric acid, and 
s g. ammonium chloride. Heat on steam bath for 5 
minutes, dilute with boiling water to 400 c.c., boil, filter, 
wash, ignite and weigh the insoluble. Examine for 
silica, clay, barytes or asbestine. 


ANALYSIS OF PAINT MATERIALS 363 


Precipitate the lead in the filtrate with hydrogen sul- 
phide, filter and wash. Dissolve in hot dilute nitric acid, 
and determine as usual. Report as PbSO,. The fil- 
trate is boiled to expel hydrogen sulphide, a few drops 
of nitric acid, ammonium chloride, and ammonia in excess 
are added to precipitate iron and aluminium. Calcium 
is determined in the filtrate as usual. Report as CaSQ,. 


II. By G. W. Thompson, (Jour. Soc. Chem. Ind. 15, 432) 

“The qualitative examination for the elements pres- 
ent may be determined as follows: Effervescence with 
concentrated hydrochloric acid indicates carbonic acid, 
sulphuretted hydrogen if zinc sulphide is present, or sul- 
phurous acid if lead sulphite is present. These latter 
two may be recognized by their odors. Boil a portion 
of the paint with acid ammonium acetate and test a 
portion of the filtrate for sulphuric acid with barium 
chloride. Test another portion of the same _ solution 
with sulphuric acid in excess for lead and test filtrate 
for zinc by making alkaline with ammonia, and adding 
ammonium sulphide. Test another portion of the am- 
monium acetate solution for lime by making alkaline 
with ammonia, adding ammonium sulphide, filtering and 
adding ammonium oxalate to filtrate. The portion 
insoluble in ammonium acetate, in the absence of sul- 
phite of zinc and sulphate of lead may be barytes, China 
clay, or silica. The qualitative examination of this 
residue is best combined with quantitative examination 
given further on.”’ 

“The oxids and elements, the presence of which is 
usually possible in a white paint, are: carbonic acid, 
water (combined), sulphuric acid, sulphurous acid, sulphur 
(combined as sulphide), silica, barium oxid, calcium 
oxid, zinc oxid, and zinc combined as sulphide, lead 
oxid, aluminium oxid.” 


364 CHEMISTRY AND TECHNOLOGY OF PAINTS 


“In the absence of sulphuric acid, the lead soluble in 
acetic acid may be directly calculated to white lead.” 

“Sulphuric acid may exist in two conditions, in one 
it is soluble in ammonium acetate, and in the other, as 
in barytes, it is insoluble in ammonium acetate. That 
soluble in ammonium acetate may be determined by 
precipitating with barium chloride in that solution. 
Sulphuric acid in barytes is best calculated from the 
barium present, and determined as described later on. 
Sulphurous acid may be determined by oxidation to sul- 
phuric acid, or its determination may be based on the 
insolubility of lead sulphite in ammonium acetate. For 
instance, one portion of the sample is oxidized with 
nitric acid and the total lead determined. Another 
portion is treated directly with ammonium acetate, and 
the lead soluble in that menstruum determined. The 
difference between the two determinations is the lead 
present as sulphite, from which we may calculate the 
sulphurous acid present. Sulphur as sulphide is always 
present as zinc sulphide, which is never used in the 
presence of lead compounds. It may be determined by 
oxidation with bromine water and precipitation with 
barium chloride, or by determining the zinc insoluble 
in ammonium acetate. Silica may be determined by 
treating the matter insoluble in ammonium acetate with 
hydrofluoric acid and sulphuric acid. The loss on 
ignition is silica, or it may be determined by fusing the 
residue in the regular way. Barium oxid is determined 
by precipitation with sulphuric acid from hydrochloric 
acid solution of that part of fused residue insoluble in 
water.” 

Raprp METHODS FOR WHITE PIGMENTS 


‘Sample 1 is a mixture of barytes, white lead, and 
zinc oxid. 


ANALYSIS OF PAINT MATERIALS 365 


“Two I-gram portions are weighed out. One is 
dissolved in acetic acid and filtered, the insoluble matter 
ignited and weighed as barytes, the lead in the soluble 
portion precipitated with dichromate of potash, weighed 
in Gooch crucible as chromate, and calculated to white 
lead. 

“The other portion is dissolved in dilute nitric acid, 
sulphuric acid added in excess, evaporation carried to 
fumes, water added, the zinc sulphate solution filtered 
from, barytes and lead sulphate and precipitated directly 
as carbonate, filtered, ignited, and weighed as oxid. 

“Sample 2 is a mixture of barytes and so-called sub- 
limed white lead. 

“Weigh out three 1-gram portions. In one determine 
zinc oxid as in Case 1. ‘Treat a second portion with 
boiling acetic acid, filter, determine lead in filtrate and 
calculate to’ lead oxid. Treat third portion by boiling 
with acid ammonium acetate, filter, ignite, and weigh 
residue as barytes, determine total lead in filtrate, deduct 
from it the lead as oxid, and calculate the remainder 
to sulphate. Sublimed lead contains no hydrate of lead, 
and its relative whiteness is probably due to the oxid of 
lead being combined with the sulphate as basic sulphate. 
Its analysis should be reported in terms of sulphate of 
lead, oxid of lead, and oxid of zinc. 

“Sample 3 is a mixture of barytes, sublimed lead, and 
white lead. 

“Determine barytes, zinc oxid, lead soluble in acetic 
acid and in ammonium acetate, as in Case 2; also deter- 
mine carbonic acid, which calculate to white lead, deduct 
lead in white lead from the lead soluble in acetic acid, and 
calculate the remainder to lead oxid. 

“Sample 4 is a mixture of barytes, white lead, and 
carbonate of lime. 


366 CHEMISTRY AND TECHNOLOGY OF PAINTS 


“Determine barytes and lead soluble in acetic acid 
(white lead) as in Case 1. In filtrate from lead chromate 
precipitate lime as oxalate, weigh as sulphate, and cal- 
culate to carbonate. Chromic acid does not interfere 
with the precipitation of lime as oxalate from acetic acid 
solution. 

‘Sample 5 is a mixture of barytes, white lead, zinc 
oxid, and carbonate of lime. 

‘Determine barytes and white lead as in Case 1. 
Dissolve another portion in acetic acid, filter and pass 
sulphuretted hydrogen through the boiling solution, filter, 
and precipitate lime in filtrate as oxalate; dissolve mixed 
sulphides of lead and zinc in dilute nitric acid, evaporate 
to fumes with sulphuric acid, separate, and determine 
zinc oxid as in Case 1. 

‘Sample 6 is a mixture of barytes, white lead, sub- 
limed lead, and carbonate of lime. 

‘Determine barytes, lead soluble in acetic acid and in 
ammonium acetate, as in Case 2, lime and zinc oxid, as 
in Case 5, and carbonic acid. Calculate lime to car- 
bonate of lime, deduct carbonic acid in it from total 
carbonic acid, calculate the remainder of it to white lead, 
deduct lead in white lead from lead soluble in acetic acid, 
and calculate the remainder to oxid of lead. 

“Sample 7 contains sulphate of lime. 

‘“Analyses of paints containing sulphate of lime 
present peculiar difficulties from its proneness to give 
up sulphuric acid to lead oxid if white lead is present. 
Sulphate of lime and white lead boiled in water are more 
or less mutually decomposed with the formation of sul- 
phate of lead and carbonate of hme. A method for the 
determination of sulphate of lime is by prolonged washing 
with water with slight suction in a weighed Gooch 
crucible. This is exceedingly tedious, but thoroughly 


ANALYSIS OF PAINT MATERIALS 367 


accurate. A reservoir containing water may be placed 
above the crucible, and the water allowed to drop slowly 
into it. This may take one or two days to bring the 
sample to constant weight, during which time several 
liters of water will have passed through the crucible. 
Another method for separating the sulphate of lime is 
by treatment in a weighed Gooch crucible with a mixture 
of nine parts of 95 per cent alcohol and one part of 
glacial acetic acid. Acetates of lead, zinc, and lime being 
soluble in this mixture, the residue contains all the sul- 
phate of lime and any sulphate of lead and barytes which 
Iiay-be present. Determine the lead and lime as in 
sample 4, and calculate to sulphates. Sulphate of lime 
should be fully hydrated in paints. To determine this, 
obtain loss on ignition; deduct carbonic acid and water 
in other constituents; the remainder should agree fairly 
well with the calculated water in the hydrated sulphate 
of lime, if it is fully hydrated. If, after washing a small 
portion of the sample with water, the residue shows no 
sulphuric acid soluble in ammonium acetate, the sulphate 
of lime may be obtained by determining the sulphuric 
acid soluble in ammonium acetate and calculating to 
sulphate of lime. The difficulty is in determining the sul- 
phate of lime in the presence, or possible presence, of 
sulphate of lead. To illustrate the analysis of sample of 
white paint containing sulphate of lime and the difficulty 
attending thereon, we would mention a sample containing 
sublimed lead, white lead, carbonate of lime, and sulphate 
of lime. In such a sample we would determine the 
lead, lime, sulphuric acid, carbonic acid, loss on ignition, 
the portion soluble in water, and the lime or sulphuric 
acid in that portion, calculating to sulphate of lime. 
Deduct the lime in the sulphate of lime from the total 
lime, and calculate the remainder to carbonate of lime; 


368 CHEMISTRY AND TECHNOLOGY OF PAINTS | 


deduct the carbonic acid in the carbonate of lime from 
the total carbonic acid, and calculate the remainder to 
white lead; deduct the sulphuric acid in the sulphate of 
lime from the total sulphuric acid, and calculate the 
remainder to sulphate of lead. The lead unaccounted for 
as sulphate or white lead is present as oxid of lead. 
Deduct the carbonic acid and water in the carbonate of 
lime and white lead from the loss on ignition, the re- 
mainder being the water of hydration of the sulphate of 
lime. 

“Sample 8 contains as insoluble matter, barytes, 
China clay and silica. 

“After igniting and weighing the insoluble matter, 
carbonate of soda is added to it, and the mixture fused. 
The fused mass is treated with water, and the insoluble 
portion filtered off and washed. This insoluble portion 
is dissolved in dilute hydrochloric acid, and the barium 
present precipitated with sulphuric acid in excess. The 
barium sulphate is filtered out, ignited, weighed, and if 
this weight does not differ materially —say by 2 per 
cent, from the weight of the total insoluble matter, 
the total insoluble matter is reported as barytes. If the 
difference is greater than this, add the filtrate from the 
barium sulphate precipitate to the water-soluble portion 
of fusion. Evaporate and determine the silica and the 
alumina in the regular way. Calculate the alumina to 
China clay on the arbitrary formula 2Si0,. Al,O;. 2H.O, 
and deduct the silica in it from the total silica, reporting 
the latter in a free state. It is to be borne in mind that 
China clay gives a loss of about 13 per cent on ignition, 
which must be allowed for. China clay is but slightly 
used in white paints as compared with barytes and 
silica.”’ 

‘““Sample g contains sulphide of zinc. 


ANALYSIS OF PAINT MATERIALS 3C€9 


“Samples of this character are usually mixtures in 
varying proportions of barium sulphate, sulphide of zinc, 
and oxid of zinc. Determine barytes as matter insolu- 
ble in nitric acid, the total zinc as in Case 1, and the zinc 
soluble in acetic acid, which is oxid of zinc. Calculate 
the zinc insoluble in acetic acid to sulphide.” 

‘Sample to contains sulphite of lead. 

“This is of rare occurrence. Sulphite of lead is in- 
soluble in ammonium acetate, and may be filtered out 
and weighed as such. It is apt on exposure to the air in 
the moist state to become oxidized to sulphate of lead. 

‘There are certain positions which the chemist must 
take in reporting analyses of white paints: 

“First. White lead is not uniformly of the composition 
usually given as theoretical 2PbCO; Pb(OH)., but in 
reporting we must accept this as the basis of calculating 
results, unless it is demonstrated that the composition of 
the white lead is very abnormal. 

“Second. In reporting oxid of lead present this 
should not be done except in the presence of sulphate of 
lead, and if white lead is present, then only where the 
oxid is more than 1 per cent; otherwise calculate all 
the lead soluble in acetic acid to white lead. 

“Third. China clay is to be calculated to the arbi- 
trary formula given. 

“In outlining the above methods we have in mind 
many samples that we have analyzed, and the combinations 
we have chosen are those we have actually found present.”’ 


ANALYSIS OF PAINTS 


Separation of Pigment from Vehicle.—The can of paint 
is weighed off and if free from water, heated on the steam 
bath for 15 to 30 minutes. Owing to the marked decrease 
in the specific gravity and the viscosity of the paint 


370 CHEMISTRY AND TECHNOLOGY OF PAINTS 


vehicle at the higher temperature, the pigment generally 
settles to the bottom very quickly. 

In the case of paints which show the presence of 
water, it is best to allow the pigment to settle out in 
the cold in order to avoid any saponifying action which 
the pigment might exert on the vehicles) [nesciear 
liquid is then drawn off as far as possible and set 
aside for analysis. The can is carefully wiped and 
weighed again. 

About 25 g. of the residue in the can are weighed 
into a tall weighing tube. A mixture of benzol and 
alcohol 1:1 is added and the contents carefully stirred 
up with a glass rod. Another tube containing a similar 
weighed quantity of the same material is balanced to 
within o.1 of a gram against the first tube, after adding 
the solvent and stirring. 3 

The two are then placed in the opposite receivers of a 
centrifuge and whirled at a moderate or high speed, 
(depending upon the facility with which the pigment set- 
tles out) for about five or ten minutes. The clear liquid 
is then drawn off, the tubes balanced, and after the 
addition of fresh solvent, stirred and again centrifuged. 
This is continued until no more of the vehicle can be 
extracted. 

The tubes are then placed in an air oven first at 80° 
C. and then at 100° C. until dry. From the weights of 
the tubes before and after extraction, the weight of paint 
extracted, and the weights of the can with and without 
the supernatant liquid, the percentage of vehicle and 
pigment can be calculated. 

There is generally left with the extracted pigment a 
small percentage of unextracted matter (probably soaps 
resulting from the interaction of pigment and vehicle, 
or linoxyn), for which allowance must be made. 


wNALY SES’ OF “PAINT MATERIALS ie 


The extracted pigment is analyzed as outlined in the 
chapter on “Methods of Analysis of Pigments.” 

Determination of Volatile Matter.'—Weigh off into a 
round bottomed flask, 50 to 75 g. of the ready mixed 
paint. Connect with a condenser by means of a steam 
trap. Pass live steam through until no more of the 
volatile oil comes over. Allow the distillate to separate 
from the water and analyze separately. Shut off the 
steam and drive air through the apparatus. At the same 
time, heat the contents of the flask to 130° C. The 
residue is analyzed for non-volatile oils. Acetone, if 
present, will be: found in the aqueous as well as oily 
layers of the distillate. 

Analysis of Non-volatile Portion Extracted from the 
Ready Mixed Paint, as Previously Ouilined.—As a rule, 
very little information can be obtained, in the present 
state of our knowledge of this subject, from the analysis 
of a varnish or the non-volatile portions of a paint vehicle. 

Most of the constants or characteristics of the various 
ingredients which go to make up the varnish are so altered 
in the process of cooking that it is often extremely difficult, 
if not impossible, to distinguish them in the final material. 

Rosin can generally be determined qualitatively and 
quite often, quantitatively, but even here it is some- 
times impossible to detect it in admixture with other 
varnish resins. 


DETERMINATION OF ROSIN 


(Twitchell Method) ” 


Fatty or aliphatic acids are converted into ethyl 
esters when acted upon by hydrochloric acid gas in their 
1 Amer. Soc. Testing Mat. Report of Comm. on Preservative 


Coatings for Structural Materials, 1903-1913. 
*}- Soc..Chem., Ind: 1891,10,,804- 


3712 CHEMISTRY AND TECHNOLOGY OF PAINTS 


alcoholic solution; rosin acids undergo little or no change, 
abietic acid separating from the solution. 

Weigh off 2 to 3 g. of the mixed fatty or rosin acids 
in a flask, dissolve in 10 volumes of absolute alcohol and 
pass a current of dry, hydrochloric acid gas through the 
solution, the flask being kept cool by immersion in cold 
water. After about 45 minutes the reaction is complete, 
when unabsorbed HCl gas escapes. 

The flask is allowed to stand for one hour to permit 
complete esterification and separation of the ethyl esters 
and rosin acids. Dilute the contents of the flask with 
five times its volume of water and boil until the aqueous 
solution has become clear. 

Gravimetric Method.— Mix the contents of the flask 
with a little petroleum ether (b.p. below 80°) and trans- 
fer to a separatory funnel. The flask is washed out with 
the same solvent. The petroleum ether layer should be 
about 50 c.c. in volume. } 

After shaking, the acid solution is removed, the 
petroleum ether layer washed once with water, then 
treated in the same funnel with 45 c.c. N/5 KOH and 5 
c.c. of alcohol. The liquids in the funnel then separate 
into: 1° a petroleum ether solution floating on top, and 
2° an aqueous solution containing rosin soap. The 
soap solution is run off, the rosin esters liberated by 
decomposition with dilute hydrochloric acid, dissolved in 
ether, and separated by evaporating the solvent on the 
steam bath. : 

Volumetric Method.—The acidified mixture is poured 
into a separatory funnel and the flask washed a few 
times with ether. The mixture is thoroughly agitated, 
then allowed to separate, the acid layer run out, and the 
remaining ethereal solution containing the mixed ethyl 
esters and rosin acids washed with water until free from 


ANALYSIS OF PAINT MATERIALS Bie 


hydrochloric acid. 50 c.c of alcohol is then added and the 
solution titrated with standard alkali, using phenolphthalein 
as indicator. ‘The rosin acids react immediately, forming 
rosin soaps; the ethyl esters remain unaffected. 

The number of c.c. of N alkali is multiplied by 0.346, 
giving the amount of rosin acids in the sample. 

The gravimetric method is the more accurate one, due 
to the difference in combining weights of the rosin acids 
in different samples of rosin. The results obtained by 
the Twitchell method are only approximately accurate. 

In the case of a mixture of rosin acids, fatty and un- 
saponifiable, saponify with alcoholic KOH and drive 
off the alcohol (after dilution with water) by continued 
boiling. Disregarding the undissolved unsaponifiable, 
the aqueous soap solution is transferred to a separatory 
funnel and shaken out with petroleum ether; this removes 
the unsaponifiable. On treating with mineral acids, the 
soap solution yields a mixture of rosin and fatty acids 
which are separated by the Twitchell process. 

In the volumetric method, the unsaponifiable need 
not be separated as above. 2 g. of the mixed acids 
and unsaponifiable are weighed off accurately, titrated 
with N alkali and the number of c.c. (a) noted. Another 
2 g. are treated with HCl gas and titrated with N alkah, 
using (b) c.c.; taking 346 as the combining weight for 
rosin and 275 for the fatty acids (palmitic, stearic and 
oleic), the weight of the rosin acids is b X 0.346; the weight 
of fatty acids is (a — b) X 0.275, and the weight of the un- 
saponifiable equals roo — {b Xo0.346 + (a— b) X 0.275}. 

Separation of Rosin Acids from Faity.— After the 
esterification process, we get a mixture of free acid and 
esters, and after titration (e.g. in the volumetric process) 
we get a mixture of rosin soap and ethyl esters of fatty 
acids. If the alcohol is distilled off and the remaining 


374 CHEMISTRY AND TECHNOLOGY OF PAINTS 


mixture treated with water, the soap is dissolved, leaving 
the esters floating on top of the soap solution. The 
two layers are separated and the soap solution, after 
washing with ether to remove traces of esters, yields 
rosin acids on acidulating. The ethyl esters are saponi- 
fied by caustic alkali and the fatty acids separated. 


DETERMINATION OF ROSIN 
(Wolff & Scholze Method) * 


Quick Titrimetric Determination.—2 to 5 g. of the 
rosin — fatty — acid mixture, according to the quantity 
weighed off, are dissolved in to to 20 c.c. of absolute 
methyl or ethyl alcohol, treated with 5 to to c.c. of a 
solution of one part of sulphuric acid in four parts 
alcohol (methyl or ethyl) and boiled for two minutes 
with reflux condenser. 

The reaction liquid is then treated with 5 to 10 volumes 
of 7 to ro per cent sodium chloride solution and the fatty 
acid esters together with the rosin acids extracted with ether 
or a mixture of ether and a little petroleum ether. The 
aqueous solution is drawn off and agitated once or twice 
with ether. The ethereal solutions are united, washed 
twice with dilute sodium chloride solution (or when the 
washed water is not neutral, to neutrality), and after 
the addition of alcohol, titrated with N/2 KOH. 

Assuming an average of 160 as the acid value of the 
rosin acids and a correction for unsaponifiable fatty acids 
of 1.5, and further taking “m”’ as the amount of the 
weighed fatty —acid—rosin mixture and “a” as the 
number of c.c. of KOH used for neutralization, we obtain 
as the rosin acid content in per cent, the following: 

Bt fee 70 
hae 


1 Chem. Ztg. 38 (1914), 369, 382. 


ANALYSIS OF PAINT MATERIALS 375 


The amount of rosin is approximately obtained by 
multiplying this value by 1.07. 

Gravimetric.—2 to 5 g. of the fatty acid mixture 
are treated as in the first method. After neutraliza- 
fen 8to..2. cic. more of alcoholic-KOH are added 
and the ethereal solution repeatedly washed with water. 
The wash water and soap solution are concentrated to a 
small volume, transferred to a separatory funnel, acidi- 
fied, and after the addition of the same amount of sodium 
chloride solution, extracted two to three times. The 
ethereal solution is dried with fused sodium sulphate and 
the ether distilled off in-a small flask. 

The residue on cooling is dissolved in 10 c.c. of 
absolute ethyl alcohol, and 5 c.c. of a mixture of 1 part 
sulphuric acid with o.4 parts alcohol are added. The 
mixture is ,allowed to stand: for 15 to 2 hours at 
room temperature. It is then treated with 7 to ro volumes 
of to per cent sodium chloride solution, extracted with 
ether two to three times, and the united ether extracts 
(after twice washing with dilute sodium chloride and 
drying with fused sodium sulphate) distilled off. 

The percentage of the thus isolated rosin acids may be 
multiplied by 1.07 in order to yield approximately the 
rosin content. 


ROSIN AND RosIN OILS 


Liebermann-Storch Reaction.— Dissolve the washed and 
dried mixed acids (obtained by saponification of the 
material to be analyzed and liberating the acids with 
dilute hydrochloric or sulphuric acid) in acetic anhydride 
on the water bath, cool and add a few drops of sulphuric 
acid (specific gravity 1.53). 

This acid is made by mixing 34.7 c.c. of concentrated 
sulphuric acid with 35.7 c.c. of water, yielding 62.53 


376 CHEMISTRY AND TECHNOLOGY OF PAINS 


per cent sulphuric acid. The presence of rosin or rosin 
oil is detected by a very fine reddish violet coloration 
produced on the addition of the acid. 

Detection.— Rosin oil may be detected by the Lie- 
bermann-Storch reaction already mentioned, or by the 
following: ! 

Stannic bromide is prepared by adding bromine drop- 
wise to granulated tin in a dry flask immersed in cold 
water until an excess is present. Then a little more 
bromine is added and the whole diluted with three to 
four volumes of carbon disulphide. The reagent thus 
obtained is stable. 

To carry out the test, a few drops of the rosin oil are 
placed in a dry test tube and dissolved in 1 c.c. of car- 
bon disulphide. Add the stannic bromide reagent grad- 
ually. If rosin oil is present, the liquid assumes an 
intense, brilliant, violet coloration. 

It may be necessary to dilute with more carbon disul- 
phide in order to bring out this color. 

On standing, a violet sediment is formed in the tube 
from which, after removing the liquid and warming the 
residue with carbon disulphide, the purple coloration 
is again obtained free from impurities. 

In the presence of much mineral oil, mix the sample 
with the solution of stannic bromide in carbon disulphide, 
and then add, drop by drop, a solution of bromine and 
carbon disulphide. This yields the coloration unmasked 
by any due to the mineral oil. 


Rosin OIL 


Rosin Spirit.— This is the lighter and more volatile 
portion obtained in the dry distillation of rosin. It is 
separated from the aqueous acetic acid layer, purified with 


1 Allen, “ Commercial Organic Analysis.” 


ANALYSIS OF PAINT MATERIALS a7 


sulphuric acid and caustic soda, and then re-distilled. 
It is insoluble in water or alcohol, but soluble, in all pro- 
portions, in ether, petroleum-ether and turpentine. The 
specific gravity varies from 0.856 to 0.883. 

Composition. — The hydro-carbons,! of which this is 
principally composed, include pentane and pentene and 
their homologues, toluene and its homologues, tetra and 
hexahydrotoluene and their homologues, terpenes, etc. 
The characteristic constituent of rosin spirit is hep- 
tine, C;Hi», (methyl-propyl-allene). The compound boils 
atetos to moA~ CG. and has a specific gravity. of 0.8031 
at 20° C. It is soluble in alcohol and ether, absorbs 
oxygen very readily, but does not affect ammoniacal 
cuprous chloride or silver nitrate. 

Rosin Oil.—This is the heavier and less volatile por- 
tion obtained after the rosin spirit has been collected. 
It generally has a strong fluorescence although the lat- 
ter can be more or less destroyed by hydrogen peroxid, 
the addition of nitro-benzol, nitro- or dinitrotoluene, 
dinitronaphthalene, or by heating with sulphur. The 
specific gravity of the crude rosin oil varies from 0.96 
to 1.1 while the refined generally has a specific gravity 
of 0.97 to 0.99. 


DETERMINATION OF WATER 


Qualitative. — Water in an oil, paint, dryer or varnish 
may be detected by adding a few c.c. of dry mineral oil 
to an equal quantity of the sample in a test tube and 
shaking vigorously with a few grains of a strong dye like 
erythrosine, rhodamine or methylene blue. Coloration 
proves the presence of water. Solvents like alcohol, 
acetone or amyl acetate which dissolve these dyes must 
of course be absent. 


1 Renard, Amer. Chem. Phys. 1884 (6) 1, 323. 


278 CHEMISTRY AND TECHNOLOGY OF PAINTS 


The presence of an appreciable quantity of water in 
an oi is indicated by the crackling produced when some 
of it is heated in a test tube beyond 212° F. 

Quantitative. —(1) In the case of non-volatile oils, about 
5g. are accurately weighed into a small evaporating dish 
or watch-glass and dried in the air oven at 1oo-110° C. 
for two hours. The loss in weight (except where volatile 
fatty acids are present) is reported as moisture. | 

For accurate determinations, however, the above 
method is open to serious objection. In the case of soya 
bean oil, for example, owing to its comparatively high 
content of volatile acids and glycerides, the results 
obtained may be somewhat high; whereas in the case of 
linseed oil the loss due to moisture may be more than 
counter-balanced by the gain in weight due to oxidation. 

With drying oils, the following method! is therefore 
recommended: 

(2) A small Erlenmeyer flask fitted with a cork 
through which pass two tubes, a long tube reaching down 
to the bottom of the flask and a short one ending just 
below the cork, is carefully dried and weighed. 5 g. of 
oil are then introduced, the flask placed upon a steam 
bath, and dry carbon dioxid, hydrogen or coal-gas 
passed through the oil for 1 or 2 hours by connecting the 
short tube to an air pump or aspirator. The flask is then 
carefully dried and weighed. 

(3) For the determination of water in oils like pine 
oil, which always contain an appreciable quantity of 
water, as well as in ready mixed paints, the method? 
outlined on the next page is very useful: 


1 Determination of moisture in oils in a current of air—Son- 
nenschein-Zeit. anal. Chem. 25, 373. J. soc. Chenmiindiean. ae 
508. 

2° Michel, ;ChemyZitegsigis se. 


ANALYSIS OF PAINT MATERIALS 379 


The substance containing water is distilled in an inert, water- 
insoluble medium, lighter than water and having a higher boiling 
point. For this purpose a mixture of toluene and xylene (1:2) is 
found most suitable. On condensing the water separates quanti- 
tatively from the toluene-xylene mixture. 

150 c.c. of a dry mixture of 3 pure toluene (b. p. 110° to 112° C.) 
and % commercial, pure xylene are placed in a 300 c.c. Jena flask, and 
the substance to be examined added. It is well to add a small spiral 
of aluminium to produce uniform ebullition. The distillate is col- 
lected in a separatory funnel about 10 cm. in diameter, and provided 
with a glass cock having a bore of at least 5 mm. A to c.c. tube, 
graduated in 0.1 or 0.05 c.c., in which the water is collected is at- 
tached. The distillate, which is milky in appearance on account of 
suspended water, is best separated by centrifuging. The amount of 
water is then read off on the graduated tube. The toluene-xylene 
may be dried over calcium chloride and used again. 


(4) Determination of water by means of calcium 
carbide (see U. S. Circular No. 97, of the Bureau of 
Chemistry). 


ANALYSIS OF OILS 


Spec Gravity.— This is determined at 15.5° C. 
(60° F.). For most technical purposes the hydrometer 
is universally used. Where, however, a greater degree of 
accuracy is desired or where the amount of oil available 
is rather small, the Westphal or Mohr’s balance, the 
specific gravity bottle, Sprengel’s picnometer or finally 
the analytical balance may be used. In the latter case 
the specific gravity is determined by means of a plummet 
suspended from one of the balance beams and immersed 
in the oil maintained at 15.5°C. The latter is contained 
in a beaker or short cylinder placed -upon a bridge so as 
not to interfere with the balance pans. 


If the plummet weighs in air a grams, in water w grams, and in 
the oil at 15.5° C. 0 grams, 


380 CHEMISTRY AND TECHNOLOGY OF PAINTS 


a—w = loss in weight of plummet when immersed in water 
= weight of vol. of water equal to vol. of plummet 

a—o = wt. of vol. of oil equal to vol. of plummet 

a— 0 





Wop Pee of oil 

For the determination of the specific gravity of 
viscous oils Lewkowitsch mentions the use of Bruhl’s 
picnometer. 

Eichhorn’s araeopicnometer is used in the case of 
very small quantities of oil. 

In the latter case also the specific gravity of the oil 
may be obtained by preparing a mixture of alcohol and 
water so that a drop of the oil remains in suspension 
wherever it is placed in the mixture. ‘The sp. gr. of the 
alcohol-water mixture is then determined by means of a 
hydrometer. 

It is advisable to determine the specific gravity at 
15.5. C. Where, however, this is not feasible a correc- 
tion! must be made. This has been found by Allen to 
be approximately the same for most vegetable and hydro- 
carbon oils, and is equal to 0.00064 for 1° C. or 0.00035 
fore ks ; 

Saponification Value.— This expresses the number of 
mgms. of potassium hydroxid necessary to completely 
saponify the glycerides and fatty acids in 1 g. of oil. 

Weigh off in a 200 c.c. Erlenmeyer flask about 2 g. of 
oil, add 25 c.c. (from a pipette) of N/2 alcoholic potash, 
and heat on the steam bath for 4 to 1 hour with reflux 
condenser. ‘The contents of the flask should boil gently, 
and should be agitated occasionally. When saponification 
is complete, cool, add 5 drops of 1 per cent phenolphthalein 
solution, and titrate the excess of alkali with N/2 hydro- 
chloric acid solution. A blank titration is made with 


1 Allen, Comm. Org. Anal. 1910, Vol. 2, pp. 49-51. 


ANALYSIS OF PAINT MATERIALS 381 


25 c.c. N/2 alcoholic potash which has been heated as 
outlined above. The difference between the two titra- 
tions shows the number of c.c. of N/2 HCl equivalent 
to the KOH required to saponify the oil. 

The alcoholic potash must be prepared from pure grain 
alcohol (95 per cent) and chemically pure caustic potash. 
Dissolve 40 g. of the stick potash in about 25 c.c. of 
water and dilute with alcohol to 1 liter. After standing 
for one day the solution may be filtered from the precipi- 
tated potassium carbonate (which the stick potash always 
contains) and set aside in a uniformly cool place. 

The saponification value of an oil is valuable as a cri- 
terion of its freedom from adulteration with mineral oils. 
It does not, however, assist in detecting adulteration with 
other vegetable oils, since most of the naturally occurring 
vegetable oils have saponification values which vary be- 
tween rather narrow limits. (See table, page 388.) 

Acid Value.—This expresses the number of mgms. of 
potassium hydroxid necessary to neutralize the free 
fatty acids in 1 g. of oil. 

Weigh off 5 to 15 g. of oil in an Erlenmeyer flask, 
add 50 c.c. of alcohol, amyl alcohol, or ether-alcohol 
mixture (1:1), add 2 to 3 drops of phenolphthalein and 
titrate against N/10 or N/5 caustic potash or soda. Of 
the above solvents amyl alcohol and ether-alcohol dis- 
solve most oils and resins almost completely. They 
are especially valuable in the case of viscous oils. Where 
alcohol alone is used it is generally best to heat it with the 
oil for a short time on the steam bath before titrating in 
order to completely extract the free fatty acids. ‘Titrate 
cold. 

In the case of resins, and especially fossil resins, the 
method must be modified somewhat. Dissolve about 1 g. 
of the sample in 50 c.¢. of a mixture of absolute alcohol 


382 CHEMISTRY AND TECHNOLOGY OF PAINTS 


and benzol (1:1) or a similar mixture of alcohol and ether 
by boiling, with reflux condenser, on the steam bath. 
Titrate against N/2 or N/s5 alcoholic alkali. It has been 
found in this laboratory that aqueous alkali yields acid 
values much higher than those obtained with alcoholic 
alkali. 

Oils which have been thickened by blowing generally 
have a lower acid value. On the other hand we have 
found that boiled bodied oils show a fair content of free 
fatty acids. 


Same Oil Boiled 
Varnish Oil and Bodied 
Sp. gr. 0.933 0.973 
Acid. Val. Ret 14.8 
Sapon. Val. 194.2 194.2 
Iodine Val. 193.2 Ones 


Iodine Value.— This figure represents the percentage 
of iodine chloride (expressed in terms of iodine) absorbed 
by the unsaturated glycerides and acids in 1 g. of oil. 

Hiibl Method.— About 0.15 g. of drying oil, 0.25 g. of 
semi-drying oil or 1 g. of non-drying oil is weighed off in 
a capsule, placed in a 500. to 1,000 c.c. glass-stoppered 
bottle, and dissolved in ro c.c. of chloroform or carbon 
tetrachloride. 25 c.c. of mercury iodochloride prepared 
as shown below are added from a pipette. Empty the 
‘pipette each time in exactly the same way, draining until 
one or two drops have fallen. Moisten the glass stop- 
per with potassium iodide solution, and set the bottle 
aside in the dark. If after two hours the color of the 
solution in the bottle is not a deep brownish red, 
add another 25 c.c. of mercury solution. When the 
reaction is complete the solution should contain an excess 
of iodine at least equal to the amount absorbed. For 
semi-drying oils allow 8 hours for complete absorption 


ANALYSIS G# PAINT MATERIALS 383 


of the iodine; for drying oils allow 18 hours. 15 c.c. 
of 10 per cent potassium iodide solution (or more in case 
a red ppt. of mercuric iodide is formed) are added, 
and the contents of the flask diluted to about 500 c.c., at 
the same time washing in any volatilized iodine trapped 
by the potassium iodide solution on the stopper. The 
excess 10dine in the aqueous and chloroformic layers is 
titrated against N/1o sodium thiosulphate with frequent 
agitation until the color of both layers is but faintly 
yellow. A few c.c. of freshly prepared starch solution 
are then added, and the titration continued until the 
blue color is discharged. A blank containing exactly 
the same quantities of solvent and mercury iodochloride 
solution must be set aside along with the oil, and then 
titrated after the addition of the same quantity of potas- 
sium iodide and water. 

The difference between the number of c.c. of sodium 
thiosulphate required to neutralize the free iodine in the 
blank and the excess iodine with the oil represents the 
amount of iodine absorbed by the oil; from the latter 
the iodine value can be calculated. 

To prepare the mercury iodochloride solution (1) 
25 g. of pure resublimed iodine are dissolved in 500 c.c. 
of pure alcohol; (2) 30 g. of mercuric chloride are dis- 
solved in the same quantity of alcohol in another bottle. 
On mixing the above two solutions and ailowing to stand 
for 12 to 24 hours a solution of mercury todochloride is 
formed containing 1 molecule of iodine (I,) to one mole- 
cule of HgCl.. The mixed solution cannot be used for 
_making iodine value determinations when it is older than 
24 hours. However, the two solutions in themselves 
will keep indefinitely. It is therefore best to prepare 
only as much iodochloride solution as is required. 

The sodium thiosulphate solution is made by dis- 


384 CHEMISTRY AND TECHNOLOGY OF PAINTS 


solving 25 g. of the crystals in 1,000 c.c. of ‘water. It 
may be standardized by either of the following methods: 


(a) Against Potassium Permanganate 


Dissolve 1 or 2 g. of pure,potassium iodide in a 400 
c.c. flask, using a small amount of water; add 5 c.c. of 
hydrochloric acid (1:1) and then 20 or 25) cle, of sau 
accurately standardized N//10 potassium permanganate 
solution; the liberated iodine is titrated with the sodium 
thiosulphate solution after diluting to 200 cc. The 
reaction involved is indicated below: 


2K MnO,+ 10oKI1+ 16HCl = 12K Cl + 2MnCl, + §H,0— Tor, 


(b) Against Potassium Dichromaie 
K,Cr.0;-+ 6KI-+14HCl = 8KCl+ 2CrCh,+ 7H,0 + 61 


Weigh off accurately 3.8633 g. of pure potassium 
dichromate and dissolve in exactly 1,000 c.c. of water. 
This quantity of dichromate solution is equivalent to 
exactly 10 g. of iodine liberated according to the above 
equation. In a 600 c.c. Erlenmeyer flask place to c.c. 
of ro per cent potassium iodide solution and 5 c.c. of 
hydrochloric acid (1:1), and add exactly 20 c.c. of ,the 
dichromate solution from a burette. Dilute to 300-400 
c.c. and titrate against sodium thiosulphate after adding 
starch solution. The end point is indicated by a change 
in the color of the solution from deep blue to pale green. 

The starch solution is best prepared, as needed, by 
shaking up about 0.5 g. starch with 50 c.c. of water, 
heating, and boiling for 1 or 2 minutes. The solution 
should be cooled before being used. The dichromate 
solution keeps indefinitely and may be used for stand- 
ardizing the thiosulphate solution, the strength of which 
varies slightly with age. 


ANALYSIS OF PAINT MATERIALS 385 


Wys Method.— Dissolve 13 g. of iodine in glacial 
acetic acid, and determine accurately the amount of 
lodine present, using 25 c.c. for the determination. Then 
pass dry chlorine gas into the solution until the color 
changes suddenly from deep reddish brown to pale yellow, 
due to the complete transformation of the iodine into 
iodine chloride. The iodine equivalent of this solution 
must be exactly twice that of the original iodine solution. 
If a titration shows more than double the iodine equiva- 
lent, there is an excess of chlorine and enough iodine 
should be added to combine with it. If the analysis 
shows less than double the amount of iodine there is still 
an excess of iodine and more chlorine should be added. 

The iodine value determination is carried out exactly 
as in the case of the Hiibl method; the time of absorp- 
tion, however, is very much less, being 4 hour for non- 
drying oils, t hour for semi-drying oils, and 2 to 6 hours 
for drying oils and marine animal oils. 

According to Allen, absorption in the case of oils of 
low iodine value is complete in 4 minutes, while those 
of higher value require not more than 10 minutes, provided 
too much oil is not taken. In this laboratory we have 
made it a practice to allow about 1 hour for semi-drying 
and drying oils. 

The values obtained by the Wijs method are as 
accurate as those obtained by the Hiibl method, and agree 
very closely with the latter. 


BROMIDE TEST 


It has been found! that on treating the ethereal 
solutions of certain oils with a slight excess of bromine, 
an insoluble precipitate is obtained. 


1 Hehner & Mitchell, Analyst, 1898, 23, 313. 


8 ie 


386 CHEMISTRY AND TECHNOLOGY OF PAINTS 


Method. — Dissolve 1 or 2 g. of oil in 4o c.c. of 
ether, add a few c.c. of glacial acetic acid (the precipi- 
tate formed with bromine is more granular when the acid 
is used), stopper the flask, and cool to 5° C. Add 
bromine, drop by drop, from a very fine pipette until the 
brown coloration persists. The temperature must not 
be allowed to rise. 

Allow to stand for 3 hours at 5° C., filter (preferably 
by suction), and wash four times with ice-cold ether. 
The residue is dried in the water oven and weighed. 

The insoluble bromides obtained from linseed oil melt 
at 140 to 145° C. and contain about 56 per cent bromine. 
Those obtained from marine animal oils decompose be- 
fore melting. This property, therefore, furnishes a good 
method of detecting small amounts of the latter in 
linseed oil. 

The bromide test is useful in the examination of 
boiled and bodied oils. Lewkowitsch' has found that 
the process of boiling linseed oil decreases the yield of 
insoluble bromides. 

On the other hand, an oil which has been bodied by 
blowing at a low temperature will give as high a yield 
of bromides.as the oil from which it is prepared. 

Lewkowitsch recommends that the mixed fatty acids, 
carefully prepared in an atmosphere of carbon dioxid 
or hydrogen, be used in making the bromide test. The 
precipitate then obtained is much easier to filter than 
when the oil is used. 

According to Eibner and Muggenthaler,? the bromide 
test is carried out as follows: 

2 g. of the mixed fatty acids are dissolved in 20 c.c. 
of dry ether, and cooled to minus 10° C.; 0.5 c.c. 


1 Farben(Ztg., 1012aac: 
2 Muggenthaler, Inaug. Dissert., r912, Augsburg. 


ANALYSIS OF PAINT MATERIALS 387 


of bromine are added, drop by drop, from a very fine 
pipette, allowing about 20 minutes for the addition of 
this amount of bromine. Another 0.5 c.c. of bromine 
are then added in to minutes’ time. The temperature 
must not go beyond — 5° C. The flask is corked and set 
aside for 2 hours at — 10° C. The solution is then filtered 
through a weighed asbestos filter, and washed 5 times 
with dry ice cold ether, using 5 c.c. each time. 

The precipitate is then dried for 2 hours at 80 to 85° 
and cooled in a dessicator. 


HEXABROMIDES BY THE ABOVE METHOD 


Fatty Acids from Per Cent 
An a la Fi se gs cao A os 64.12 
Seineee il baltic) eee. cw oe. 57.96 
Pipceen Ole DUtCR) vow is has eh Brig, 
Persea Oil a Plata) 2. Sy, on wn 51.66 
ree IL Vall ohn ss steak S050 
CLINT: BRED REY RIEL es ea oo aa nil 
Soya Bean Giles ye heed ido ce. Lalu ers 
Peep emee dle: or Ih <s ditG. oa ee es erent 


The melting point of the bromides obtained by Eibner 
and Muggenthaler from the mixed fatty acids of linseed 
Gilewas, 177 °C. 

The following table will give an idea of the yield of 
bromides obtained from various oils: 


Material Per Cent} 
errata an Me la ie se el COR 53.6 
Linseed (iodine value 181.)...... OO Aes 
Linseed Oil (iodine value 186.4)....... 24.47 
Linseed Oil (iodine value 190.4)....... Be 
BANOO ah deena Koes fate See ae nil 
PBI SOCCM DL coat ota ne hae 8.82 
AVR ETT ee Dildo ey me, eos eR rink ta ae: I.42:1.9 
HOV Ee HeAN SUES re CMe beaks shi aa aie aera 
PROUT Vee Cty ING Renee cee ene agees nil 


1 Lewkowitsch, Vol. I, p. 477. 


288 CHEMISTRY AND TECHNOLOGY OF PAINTS 


Material Per Cent 
SOvarbéat Ole ces, tk eee eee 3.62 
CormsOils 2. Se eee 2 ee ee nil 
Cottonseed. Oil 2 ae a ee ry 
Menhaden Oils 4 geet ces ee 61.8 
CodiOils tien ge ee 40.685 20962 
Séal us e320 ce te eee 27554) Bynaye 
Whalé Oil oo 22 oe eee ee ee ES 64 2.28 


SoME CHARACTERISTICS AND VARIABLES OF COMMERCIAL BOILED OILS 





Description 


Somewhat thin and fluid......... 
Very, VISCIGG epee cere re ene 
‘Tacky; yielding strings “9-2. ae. 


Vertycstoute itt oan ae ee 
Solid 427 tere deathae pears ie eae 


Varying in consistence in the 
same order, from thin to very 
VISCOUS; Geis. ake es ee 


Double boiled oil, lee 
= pigs bt eres (ee ek ee 


* ae aed UREA rot ERE 
Commercial boiled oils, 8 samples. . 








ea Saponifi- 





alls cadbe. is" 





value vane: nae 
value . 
Per cent 
13 , Aco ere IOI.3 
24.0 ie eee row. 
33. 002g a eee 73.9 
foes 188 :1=[o2) @45 ae ee 
ath ae ieee TAQ. F=L§ 394 
8.85 {$252.7 | aero 
7200 1S0k0 451.0 aoe 
12 143 170 *S1s see 
19.69 180235 faa, eee 
20.89 Tog 6! Aes 
24.97 TOS Cod tia 
14.02 1637-0") Oe eee 
4.8 188.7 159.0 
ue 189.1 100.7 
qo 189.1 95.6 
Qs 186.6 83.6 
Ont Ral weed 79.1 
pte 18722 yO.2 
18.8 192-3 yee 
ers 191.0 161.0 
0.98 19253 ste: 
3.00 19275.) emi 
2.8-6.4 187:5= | 180.4 h1oses 
192.2 


CHARACTERISTICS OF BOILED O1Ls (LEWKOWITSCH) 





Name Specific gravity 





Teinseed Oil {ra we 2 aoe eee ie 
Pale boiled linseed oil... .. 
Double “ - yen eS 
Ozonised ‘a Ane. 

(a9 ce ce 
(74 “ec eee eae be 





OF OF OFORZOEO 


.9308 
-9429 
-9449 
.9310 
.9388 
9483 


Ether-insoluble 








Iodine value | bromides from 
glycerides 
Per cent 
186.4 OMe 4 
171.0 20.97 
169.96 13.03 
180.1 2620-30) a4 
ryt 25 78 
169.7 30.19 


ANALVSIS OF PAINT MATERIALS 389 


REFRACTOMETRY 


In testing transparent liquids (or solids) for purity 
or concentration, the determination of their refractive 
index offers one of the most valuable aids. Refractive 
index is a physical property, fully as characteristic as 
boiling point or specific gravity, and is more readily ascer- 
tained than either of these. In fact, by means of a modern 
refractometer, the refractive index of a sample can be 
accurately ascertained in less than a minute. Its deter- 
mination should form part of the routine examination. 

The most convenient method of determining the re- 
fractive index is by means of an Abbé refractometer. 
A drop of the liquid under examination is placed between 
the two prisms, light reflected through them by means 
of a mirror, and the movable telescope tilted until the 
border line, which appears in the field of view, lies at 
the point of intersection of the cross hairs with which the 
telescope is provided. The refractive index is then read 
off directly on the scale mounted at the side of the telescope. 
Divisions of the scale represent units in the third decimal, 
and tenths of a scale division can be estimated so that 
the reading is accurate to within about two units of the 
fourth decimal. In order to make use of this high degree 
of accuracy in the division of the scale, it is necessary to 
have the border line, as viewed in the telescope, sharply 
defined, or else the point of intersection of the cross hairs 
cannot be brought accurately in line with it. 

As a matter of fact, when it first comes into view, the 
border line is apt to be poorly defined because of its being 
more or less colored. As is well known, the amount of 
bending (refraction), which light undergoes in passing from 
one transparent body to another, is not only dependent 
upon respective refractive indices of these bodies, but is 


390 CHEMISTRY AND TECHNOLOGY OF PAINTS 


also dependent upon the wave length of the light, shorter 
waves (towards the blue end of the spectrum) being bent 
more than longer waves (towards the red end). The result 
of this is, when white light passes from one medium to 
another, its component parts become visible as a colored 
zone. Obviously, to characterize the refractive index of 

























































































Vier 
































No. 112. ABBE REFRACTOMETER 


a substance, it is necessary to state the wave length of 
light for which the refractive index was measured. For 
most practical purposes, the sodium ‘‘D” line is used as 
a standard. 

The use of monochromatic light, however, is less con- 
venient than white light (daylight or artificial), and, by 
means of a simple device, the Abbé refractometer permits 
ascertaining the refractive index for the ‘‘D” line with 


ANALYSIS OF PAINT MATERIALS 301 


the employment of white light. This result is made possible 
by means of a compensator inserted in the path of the 
light entering the telescope after it has passed the substance 
under examination. The compensator consists essentially 
of two sets of dispersion prisms which can be rotated op- 
posite each other so that the degree of dispersion they 
offer can be varied from zero to double the amount pro- 
duced by a single set. In this manner, any degree of dis- 
persion produced by the substance under examination may 
be compensated. The actual procedure of operation 
consists of turning the milled head until the border line 
becomes colorless. It then is sharply defined, and lies 
at the same place where the border line would lie if mono- 
chromatic yellow light of the sodium ‘“‘D” line were em- 
ployed. While the operation of the compensator is as 
simple as the winding of a watch, its proper construction 
makes considerable demands on the instrument maker. 
In selecting a refractometer, those which do not yield a 
sharp border line should be rejected, since it is impossible 
to make an accurate determination of the refractive index 
with them. 

The difference in the amount of bending, which light 
of different wave length undergoes, is not merely an in- 
convenient complication, which must be made harmless, 
but constitutes a further valuable characteristic property 
of the substance under examination, —the amount of 
spread or dispersion that light of different wave length 
undergoes in passing through a body being also a physical 
constant of that body. Refractive index and dispersion 
do not vary proportionally. If it should occasionally 
be possible to prepare an adulterated liquid with the 
same refractive index as the authentic article, the dis- 
persion would not agree. With the aid of tables ac- 
companying the refractometer, a simple calculation gives 


392 CHEMISTRY AND TECHNOLOGY OF PAINTS 


a quantitative numerical value for the dispersion. For 
many practical purposes, however, it is sufficient to note 
the position of the graduated index on the compensator 
at which the border line becomes colorless in the examina- 
tion of an authentic sample, and then observe whether the 
border line with the compensator in the same position 
shows marked color when a specimen under question is 
examined. The amount of displacement required to ob- 
tain a colorless border line will give an approximate indica- 
tion as to the discrepancy in dispersion between the two 
_ samples. 

In all determinations of refractive index of liquids, 
the temperature should be noted. Usually, the refractive 
index increases as the temperature decreases. An Abbé 
refractometer is regularly provided with water-jacketed 
prisms through which a stream of water should be 
maintained. The temperature of the film of liquid 
under examination quickly equals that of the prisms, and 
is read off on a thermometer mounted in the upper 
prism box. 

In the examination of oils the refractometer is of 
paramount importance in view of the fact that the re- 
fractive index of China wood oil is higher than that of 
any other vegetable oil. 

China wood oil has a refractive index from 1.515 to 
13520; 

Next in line comes the Japanese wood oil which has 
a refractive index from 1.5040 to 1.5100. 

All other oils appear to be considerably below that, 
the average for linseed oil being 1.4800. 

The following is a list of the best known oils used in 
the paint and varnish industry.! 


1 For further information see “Refractive Indices — Oils, 
Fats and Waxes.”” Kanthack & Goldsmith, London. 


ANALYSIS OF PAINT MATERIALS 393 


(oa SU .g? alll OST Nal a ie ie a 1.4790 
Mey COCR bas tite Oe ws ats ns Lec rsatost. 520 
Stillingia Oil, otherwise known as Tallow Seed 

RE ee iio hE Pak ae one 5 I.4520 
MereneO fapanese).., . te.ih. 2a hes we he I.4747 
NN a8 GIL SES 9a Gn RIO ete a en a 1.4800 
Pree amy ete eerie. os tn tae eps ibe. 8 I.4516 
Bee eee re ot PUNT Ns ek, 1.4729 
[CLO SERS Gs Se it ee Me ee SP iedya2 
“Ee gOS THI So Fae ae eg nr a 1.4763 
Be eT ules ince Ns ser ovis Os Woes oe yea 
eC akc. Ye aah gr a) weitias Cee S DyA0L7 
AOU eet Oiles er s in hs he oie sk ee I. 4631 
ern) ea sok oy SEI. ay [ADU etOm A 72 


The only other oil which has a high refractive index 
is rosin oil, light brown and yellow, running as high as 
Eeeoyooto 1.5548, and some dark Se which run 
from 1.4748 to 1.4877. 

All of the above figures are only approximate, as al- 
most every sample of the same oil differs from the third 
decimal on. 


394 CHEMISTRY AND TECHNOLOGY OF PAINTS 


THE CONVERSION OF FRENCH (METRIC) INTO ENGLISH MEASURE 


1 cubic centimeter = 17 minims. 
2 cubic centmeters =-" 345: 
3 . id 51 6c i 
4 a = 68 ‘* oridram ~ 8 minimis. 
S ce as 85 ce “ I oe 25 (<9 
6 ‘6 Ss: " “oy 6c 4I 6c 
7 ce as TTS ‘ (a3 I (x9 58 cc 
8 - re ae 2: rans eG ares 
9 (<9 <s 152 ce (79 2 (a9 Ee: (74 
Io (9 es 169 ce ce 2 iz 40 (<9 
20 (<9 = 338 ce é 5 (73 38 ce Se 
30 # = S07 = “tounce odram 27 minims. 
40 = = 676 ‘ ee 3 drams 16 = 
(29 (73 (a9 (<9 (a4 iz 
fo) 78 I 6 5 
5 ce me 45 “ce “ec (a9 > ce 
60 = I0r4 2 ounces oO 54 
ce (7 ce “cc (79 “ee 
fe) = 116 2 
‘ ce me, 3 (79 ce “cc . ce 43 ce 
. 6c S 7352 (a4 (a9 7 ce “c 3? ce 
° = F521 I 21 
eh (9 we eae (a9 ce : (79 (79 Io 6c“ 
1000 a = 1 liter = 34 fluid ounces nearly, or 2} pints. 


THE CONVERSION OF FRENCH (METRIC) INTO ENGLISH WEIGHT 


The following table, which contains no error greater than one-tenth of a 
grain, will suffice for most practical purposes: 


Igram = 15% grains. 

2-prains = > 405 73" 

3 a3 ay 464 ce 

y eae et WE coe Oe eee ele) > or «tdram_ 1# grain. 

RE crs Pe ee ee EY ey led BE ett fo ogo 

Serer She te: eerie See (CDG eee 

y Seon we sah Pee pee ele re “2 a ae “ 

Bo SE ree a 9 Bie aes arene ce “99 drams 732 : 

Oe csi ae RRB esate eh ae Me Ye tse ey 
TO. 2." p wee LAS eae re eee ae es! 
TE. 2s Seh60 £ an eae (S - By RS ays aeee 
12-2 3. ols. TBS ars Se eres ee eee te 
13 Sk pe AO0F tae ee eee ea C4 \ a ae 
14 42st see" Area 8 gle eee 3 
15 Scar Be oO anes Sere ¢ (250 \oes Lee 
16 ‘< = 247 HO AY Se Aes « 4 ““ 7 6c 
Ty: < Site Ace PG ae teu ie ohana eee Weg e 8 
T°): OE: Wee NS ak eae ete A ea ee 
ca memes 1 
os ““ % 3085 ia eae “< 5 é< i “ 
3 ce a 4 3 ig ee a «6 7 iz 43 | ce 
40 me: JOLY eit) aah ae eh 10 17$ 

56. Be Ae 77 ene biel 12) Sees he 
60° = 26 S. fike APiyaee eit a Le eee " 
70: Mit OSOE hae s ae renee 160) eee 
fe er LY MM RR A | 20") eae eae 
go. “= 1389 Tepito ee east tacy 9 . 
T0048)! 4 PL 4a Aer ee ae ae ps ES aks ae 


1000 = 1 kilogram = 32 02,, 1 dr., 12¢ gr. 


ANALYSIS OF PAINT MATERIALS 


395 


Metric SYSTEM OF WEIGHTS AND MEASURES 





Measures of Length 





Denominations and Values 


Equivalents in Use 








MVliy GIS MECOR eels aches Ale es ole wees 















































10,000 meters. 6.2137 miles. 
Relomener de ita Slums ches I,000 meters. .62137 mile, or 3,280 ft. ro ins. 
PIECLOMELEEA tes 6 ste P's, Swiss + roo meters. 328. feet and 1 inch. 
WDekanmevenase ays ton aeke «oles Io meters. BORN inches. 
WATE: has Ne at an eer pO I meter. 200871 inches. 
ID ECINOECI Wier eels faces es ishe aig hia ce 1-roth of a meter. 3-937 inches. 
Centiinetenat 2s. asa. 23% ee 1-rooth of a meter. .3937 Inch. 
MUlliiMeberttuioe a> so. Wes aos toes 1-rocoth of a meter. .0394 inch. 
Measures of Surface 
Denominations and Values Equivalents in Use 
[Seeing 135.3 Seon, 8 Ue cae eee eee 10,000 square meters. 2.471 acres. 
Ge Ba ere Go Ba Oe ee 100 square meters. 119.6 square yards. 
CSS ORE 3 OO Oe I square meter. 1,550. square inches. 
Measures of Volume 
Denominations and Values Equivalents in Use 
N ee Cubic M M i 
ames Livers ubic Measures Dry Measure Wine Measure 
Kiloliter or stere.}| 1,000 t cubic meter. 1.308 cubic yards. 264.17 gallons. 
Hectoliter...... 100 | 1-roth cubic meter. 2 bu. and 3.35 pecks.} 26.417 gallons. 
Dekaliter....... Io ro cubic decimeters. g.08 quarts. 2.6417 gallons. 
1 ihe) ees eee I t cubic decimeter. .908 quart. | 1.0567 quarts. 
Deciliter.......| 1-10 | 1-roth cubic decimeter. 6.1023 cubic inches. .845 gill. 
Centiltter......;| 1-100 10 cubic centimeters. .6102 cubic inch. .338 fluid oz- 
Milliliter....... I-1000 1 cubic centimeter. .o61 cubic inch. 27 9 fled 3 
Weights 
Denominations and Values Equivalents 
in Use 
ee Number of Weight of Volume of Water Avoirdupois 
: Grams at its Maximum Density Weight 
Millier or Monneaw.... oa8. he8- 0 1,000,000 I cubic meter. 2204.6 pounds. 
MUTE SL hee ee a PSR yen’ sie 6 100,000 r hectoliter. 220.46 pounds. 
jc Ggase' He biol =: Sone ene ao 10,000 ro liters. 22.046 pounds. 
Bevloeramivar mail ascii 0. sho ee 1,000 r liter. 2.2046 pounds. 
PLECEORMAI Gees er niers Si eGue ental I0O I deciliter. ; 3.5274 ounces. 
WGA rane ea a leyals, panies so cote Io Io cubic centimeters. -3527 ounce. 
Oeil pen acme ere avs Cheon Nae ae it 1 cubic centimeter. I5.432 grains. 
Weisner Selene oa I-10 r-roth of a cubic centimeter. I. 5432 grains. 
(CEN EIS CE col Giiee, Naren hae lara I-100 to cubic millimeters. .1543 grain. 
A indll bad anaes oe Meee ieee gee eae ae I-1000 1 cubic millimeter. .O154 grain. 














For measuring surfaces, the square dekameter is used under the term of ARE; the hectare, or 100 
ares, is equal to about 24 acres. The unit of capacity is the cubic decimeter or LITER, and the series 
of measures is formed in the same way as in the case of the table of lengths. The cubic meter is the 
unit of measure for solid bodies, and is termed STERE. The unit of weight is the GRAM, which is 
the weight of one cubic centimeter of pure water weighed in a vacuum at the temperature of 4 deg. 
Cent. or 39.2 deg. Fahr., which is about its temperature of maximum density. In practice, the term 
oe centimeter, abbreviated c.c., is generally used instead of milliliter, and cubic meter instead of 

lloliter. 


306 CHEMISTRY AND TECHNOLOGY OF PAINTS 


SPECIFIC GRAVITY OF VARIOUS MATERIALS 


AceUCAC epcew Sone ae 1.0607 3 
A CELOHE Were iste oe te .788-.790 
Acetylene 0004. tek .Q2 
ACEC ACIGits sam aier 1.0621 4 
Agaté= a ve nee. eee oe 2.5-2. a 
Alabaster ttc. see 2.3-2.8 
Aluminium, Oxides 35200. 3:75-3:00 
ir Sulphate..... 2d 
r “ 18H2O 1.62 
Ahim,-Potassium, ose Las 
aS SS SOGH an er een ee 1.65 


‘¢ Ammon. Chrome. .1.719 


‘‘  Potass. Chrome. . .1.81278 (0. °) 
A mDeELa) apie a tase 1,0=1.1 
Ammonia*(eae)ee. 0. & O71 
fe (liq.) .6234 (0.°) 


Ammonium Carbonate 
NH,HCOs. . 1.586 


we Chloride... . 1.520 (17. 2 
si Nitrate;..c. 2 1.725 (15. | 
Sulphate. . ..1.7687 %& 
ns “ “acid 1. 787 
Amy]l ‘Acetate..... +2 38792'(20. ) 
Alcohol wees ee .8144—.8330 
‘““- Valerianate.._.icuw) oT2no.,) 
Anilin@eg. os eater 1.0276 (12.°) 
Anthracene = y.. Geo. ee 1.147 
Anthracites.4 2. 2, shoe 1.4-1.7 
Antimony Oxid) /Urixeesesc2 shay 


Tetra . .4.07 
f jen eeDiasges: “8 
runes 4.120 (0.°) 


“ec 


Arsenic Disulphide. . 2A=3.6 

SPR RCNIORIC occur 3.990-4.25 

ee FIX eae Ane 3.646 
Asbestos; sateen ee t.4 
Asphalt. se: ‘San Pen ae {i055 
Barium Carbonate. .....4.27-4.37 

‘“‘ Chloride 2H20.. .3.007 7¢ 

leek CLOXIG 2 uy rae 4.958 

‘(etesulphide, ystae 4.25 

: Sulphate; WG, 4.33-4.476 
Barleyecat Got ee ae .51—.00 
Barytes: ie . ena 4.476 
Basalts\.3.44:n- a: Sa Diy—202 


Bees Wax (see wax). 
Beefsuet jad Oe eG meee et 
ce 


Rie, ee Wace. S .968 
Bellmetal 5 2. cote 8.81 
Benzene b. p. 80.5° C.... .8799(20. ae: ) 
Benzoic Acid kek eae hae 1.201 (21. 
Blanc: Fixes at ee ae 4.02-4.53 
Blue Vitrioly 7. .0weee 2.27 
Bones oi... ce, See 1.7-2.0 
BorieAcid: 4 4 ce eee 1.46 
BuLteryo ten oes eee .865—.868 


ButyricAcidina:, eae 9599 


admium Sulphide (artif.). . . 3.9-4.8 C 
““ (Greenockite) . 4.8-4. 9 


Calcium Carbide aan 2523 
Carbonate. . 2572-2205 

- Chloride : H:0)r. 654 

% . 2,26 

“ Fluoride. . a a 

. Hydroxid. . ee <2. O7n 

“< Oxide ee 3.15—-3-40 

- Sulphate. -%. += 2.904 

o (Gypsum)...... 2.32 

= Sulphide... 23.7 4.2.8 

i Tungstates. = 6.062 
Camphor. )..555se eee .992 
Caoutchouc. 22... .92-.96 
Carbolic AC.) sae 1.0597 (33. ) 
Carbon (Amorphous). . . .1.75—2.10 

“¢ - .(Graphite).+.". .2.t0-2-505 

“(Diamond eee 3:47-3-5585 

“t= Diogid a ; ehee 

ty Disulphide. . 1.28 

“< - Monoxid.32eeses 0.067 

‘“*. "Tetrachloridesy, 1-50 
Cast Tron? yaaa wean 
Cellulose = 3455. aeeniee T.29=FA5 
Charcoal (Airfilled). . 0.4 

(Aintree eae cee 1.4-1.5 
Chlorine? =: 2-222 eee 2.491 
Chlorefotm33)5 ee 1.5204 
Chrome Alum Cre(SQx)3. 

KySOxq. 24H2O a aeaces STEN 1.81278 
Chromic Oxid;2aan sess 
Chromium. eae 6.92 
Chromium Trioxid..... .2.67—2.82 
Citric Acid 3 ake eee 1.542 
Clay “7. 0 ae 3. eee 
Cobalt Chloridesaaae emer 2.04 
Cobaltic Oxid (Co203) .. .4.81-5.6 
Cocoabutter (m. p. 33. mas. 

34. CG). : kau ee .89-.91 
Copal, ... Sees eee 1.04-1.14 
Copper é«.-: 3s eee 8.91-8.96 
Copper Carbonate, Basic. 3.7—4.0 
Cork. cs: Se eee 24 
Corundum=. 2: 2 ee 4.0 
Cottan.(Airdry ) eee 1.47-1.5 
Cryolite AlF33NaF. 12.6 
Cupric Hydroxidl ae 3.308 

“<’ Oxid- (Black cae 3 32-6.43 

‘“<  Subpha tess eee 25816 

‘“‘', Sulphate (5H.O),. 2.284 — _ 

“« _. -Sulphidevwes eee 3.8-4.16 


Cuprous Oxid (Red) a. 5-75—0.09 
Cymene b. p. 175.°-176.° 0.862 (20.°) 


Dextrin®. 2. 4) ee 1.0384 
Diamond ’y, "22 3.40-3-52 
Dolomite. cen: © see 2.9 


ANALYSIS OF PAINT MATEIRALS 


SPECIFIC GRAVITY OF VARIOUS MATERIALS — Continued 


Earth: 
CAV EINE ess. se 1A 
Hecht Oe oe Regie int’ 
ES ee Oe naa ena 1.34 
eURAD RV Gt NT ret a oe. os 1.6-140 
Vert Si ieee er 1.036 
Father (Diethyl)... 2. 0.7183 (17.°) 
penyl Acetate... 5. .8920-.9028 
Ethyl Alcohol}... >... 7937 ty 
Pee Dee ee, .9784 
Eeicalyptol.. > 2. Beane es ee (20. ) 
MIBENOL Gt oe oy SS. 0630 (18.°) 
Perro Chloride: a. 2.804 (10.8 ) 
Pe tA Varexid: s; . .4 s 63.4-3.0 
OSI See es 5.12-5.24 
Ferrous Carbonate... .. .3.70—3.87 
ss sulphates::...... 1.86-1.90 
Sulipmide.. f..7.. 4.75—-5.04 
MASAI). 5 es 2: 5 
LE 01S ie i ae eae 0.920-0.928 
Formaldehyde (—20.°).... .8153 
Formic Acid ieee ee I.219- 25° 
cL ee 1.244—0 
PUA DICOA CIOL pee oe .cae 1.625 
Purina eae 1.1504 -9 
Gasoline (b. p. 70°.-90.°). .66-.69 
Cres ALOR? a tak 1.88 
Glass: 
WEINGOWs orc ok 2.6 
BVEIE EOE Muerte. 5 sos Ac 272 
eta ditt Ce ee ee 2.05 
‘UU Bee a Sits rapa Se a 250-5.9 
CUD he aan ee a 1.27 
DBS ee ie ee oo soil 2 A207 
Rot amity. Sens Sk vin. 2 2.51=3.05 
Graphite (Natural)...... 2.17—-2.32 
(Artificial). .., .2.10-2.25 
Sunenrate.. 0. aa: © 3i-1.45 
rmbtapereiane oi 6a kw GOL 
Bec Mie eaonk ees 2639 
Hemp (Airadry) 0. o.- res 
orableride 26 ty .5.253.0 
hyveriodic AGid 4 Ss! 4.3737A 
Hydrobromic Acid...... 1.278A 
Hydrochloric Acid.......1.195 (8° m 
Hydrocyanic Acid....... .697 (18.°) 
Hydrofluoric Acid....... 9879 (15. ) 
TEV OR OCC a: Pa. de a .06949 
Hydrogen-peroxid....... 1.4584 (0.°) 
Hydrogen-sulphide...... .g—1.1895 
Tydroquinone.......... 1.326 
Tacta RUbBEr 2. fos. 2 .93 
MDW Oiad a erat ete ae 


1.35 
PBOIS ANC ater: tees Va 4.629 (0.°) 


397 
A Gee Nat Rb 69 ro  r g R 4.948 (17.°) 
TOCOcOriie proc ciate wy 4.09 
Tron USAT Res een ee tee 7.85-7.88 
(gray pig).. Osyth 3 
‘(white pig). | .7.58-7.73 
BPR CEUSE Jeter es a ac ng 204 
Sa e(Wrousht) ke tachi ce, 7.00 
fe STS TUn ante (Pak meeoa ieee 4.86-5.18 
PES UIOKIC ap. teen mites ca2 
LVORV are Me oe a 7 L.02-1.02 
Japan Wax (m. p. 53.5°- _ 
BARS iti ang ees AS 992 
FR 10) iar dens, atoagaas eke oe 
Bactie-Acdis coo. nete ae. 1.2485 
Lard (m. p. 41.5-42.C.).. .92-.94 
eiware sk setae rie eee ean 2.00-3.00 
Lead (milled es 351.42 
(wire)... “fs .11.28 
“> Acetate. see oe & 2.50 
co HAGAT DONATO Mare ne: 6.43 
eS be , Basic. . .6.323-6.492 
ev OTIC se. oacst 5.8 
Mey TOMLAL over e cere aye e G@isscas 
“* Hydroxid 
(3PDOHsO) «.., 1... 7.502 
Se OCHCLE ree rte hrs," 6.12 
phe NICAL tet ck eee 4.5 
OOO. .9.2-9.5 
ss sf (Pb;O,) . Sapte. 0.000-( TS.) - 
ceeansulpliater cnc eee 6.23 
ee SUpnOCyana ten." 3.32 
ae BUNLESLALE Sis o'er 8.235 
[en Ae ees es ee me i .86-1.02 
Lime (unslacked)........1.3-1.4 
abet Eel te | een a oa 2i3=—219 
Ligestone ta. hee eer a 1.86-2.84 
Einoleume.. 225 EeD5“1:3 
Linseed Oil (raw). . 93 —.034 
is zs (boiled). . iniaaoic 
Litharge (natural)... . 2+ + 7.83-7.98 


¢ 


Lariilicia le eae 9.3-0.4 


Lithium: Carbonatesn:.c02-221 
iy Chloride: ....., . 1:908-2.074 
Malachite: se succwe ae tate. 3.85 
Manganese Chloride 
(MnCh4 HO) Biases. 1.913 
Manganese Nitrate...... 1.82 


a Oxid (MnO)..5.09—5.18 
oe “*  (Mn0O;) 5.026 
(Mn2O3)4.325-4.82 
Sulphate 


(7$ (a9 


(MnSO.7H20). 2.092 
Marble: 
APERIGart Mit cote aa ee 2.8 
British “jc ate! a cee on pa 


398 


CHEMISTRY AND TECHNOLOGY OF PAINTS 


SPECIFIC GRAVITY OF VARIOUS MATERIALS — Continued 





Marble: 

Carrara stesa sere at ee 2.72 

Egyptian, Green. . ....2.67 

Florentine G25... -235 252 

French 5.at ee aa ee 2.65 
Mail sf ee eae E.6—2.5 
Masonry: 

Ashlar Granite... 5s.62.37- 

 LAUIESTORE) a wie. 227 
“\) Milstone,’: ... 2306-2." 
“ . sandstone... .. «2.61 
Rubble (dry) a2 =. 2.27 
a (mortar) so5..4 2:42 
Meerschaumia: .cu-3 sear .QQ-1.28 
Mercuric Chloride. ....”. 5.32-5.46 
e Oxid (hota aa II.O-I1.29 
Mercuric Sulphide: 

(Hes black) 1 3.eob aoa 7.55—-7.70 

(Hp ted) S. aiee. 8.06-8.12 
Mercurous Chloride: 

(Calomet): 07a woes 6.482-7.18 
Methyl Alcohol. ........ .7984 (15.°) 
Methyl Ethyl Ether..... .7252 (0. ) 
Mica re. RN aie eee 2.65-3.2 
Milk. ows}. eee 1.028-1.035 
Milk: Sueararha. secs ae 1.525 (20.°) 
Molybdic Acid: 

Ho oO Os 3.124 (15°) 
Morphine aye ts 79 5. maa 1.317-1.326 
Mortar (hardened)..... .1.65 
Mutton Suet (m.p.47.° C.) .92 
Napthalena: ancy. wee 1.1517, : 

(reve 
Naphthol-a.. a: ate 1.224 (4.2 C} 
ms | SO Re I peer to, 8 B40) 
Neatsfoot-Oil. 2. So... .914 (39. F.) 
Niekel (ralled).20. 7. age. 8.67 

I CARY Gk sclera e 8.28 
Nicotine - iy. eae 1,011 4% 
Nitraniline:m...2o a0 ean 1.43 

rs Saas Ae Ca 1.424 
Oats: sii oi ee eras ata 
Ochiern st a ae ee 3.50 
OleiGAcidy. 3 2. ee 8908, 
(ie. 20" 
Oolitic scones: et Se 1.89-2.6 
Opalinn a isu ak Sone 2.20 
Oralit Aid so asap 1.653 (18.°C.) 
Ozone 7 oie, tt eee eee 1.658 (A.) 
PalraiticlA cin wn uceinee ene 8465 
(7 Gtos) 
Palm Oil (m. p; 30.°Ci).. > <005 
PADSrES hen cee e eee O05 
Paraffine: 
Mop 38ie $2 Cute ae Ore ed 


Mm. p..$2:-§65C. fon on o6= 08 


Pearls).2)) 3. 2°72 
Peat) 2. ches T.2-15 
Petroleum Ether: 

b.. p: 40-90; 6 ee ae .65-.66 
Phenol." 9% 125 oe eee E.0507133, 00) 
Phosphorus Shr ae 1.8232 

4 (rea). . 21% 
Phthalic Aci < siacn eee 1.585—-1. 593 

“ anhydride... 1.527. C.) 
Picric. Atidvica ase aes 1.813 
Pinene 6) S:ilccues eeeecaraem 8587 
(20.° C.) 

Pitch. 23 eee 1.07-1.10 
Plaster of Paris: a. ane 2.96 
Platinunis oe).ne eee py eny 3 
Porcelain: 

Berlin ee Me ee eee 2.29 

Meissen :<") 2). Aone 2.49 

S@VLes:.’.! ays. ease 2.24 

China 2,0: te eee 2.38 
Portland Cement....:.. 53.25-1-58 
Potash. 4.6. Gee 2.10 
Potassium. 34 eae eee 875 (13 ) 

ze Bromide.«.....4.42: 780 

ss Carbonate... . 2.29 

&§ te Sacra 043 

. Chlorate... -/2i344 (17. 3) 
sm Chloride...) AbteGa se 

iz Chromate. .. . 2. 721 Os 2 

: Cyanide 2 1.52 (16° ts, 

4 Dichromate. . . 2.692 (4°) 

3 Ferricyanide. .1.8109 an ) 
- Ferrocyanide . 1.8533 (17°) 


u Hydroxid..... 2.044 

* Todideyc. 7. 30aa3 (24.3°) 
it Nitrate: 2. ea 
Permanganate 2.70 

‘ Sulphate... .. . 2.6633 4 
Shy Acidag oe 

# Sukphide K2S.. 2.13 
Sulphocyanate 1.906 


Tartrate.: 0078 
Potatoes: <....."e eee eee 1.10 
Pumice.’ nat.)i sn oc on aes 
“*:  (AYtH joensen ee aaa 

Pyridini...2 ae eee 9855 (15. 7) 
Pyrogallol-2 2. eee 1.463 (40.-) 
Realgar Asim /5. 9). 3.4-3:0 
Red Leads 23 eu aaa 9.07 
Rosin? 2") eee Dee 
Ruby; i. sete 3.95—4.02 
Salt. (table). ae eee 2.15-2.17 
Sand (dry)}s5 7 c.aeeeeeeeee 1.4-1.65 

‘* moist). .5 eee 1.9—2.05 
Sandstone :s:..)) kee eee 2.2-2.5 


ANALYSIS OF PAINT MATERIALS 


399 


SPECIFIC GRAVITY OF VARIOUS MATERIALS — Continued 


SAUD ONES Oo re 3.95—4.02 
DETOEMEMOt a oo! 5 es 2.4-2.7 
BICOMMCIVSL a. o.s 2.49 (10.°) 
‘“‘ (graphitic) . .2,.0-2.5 
Me (amorphous) . aoe 2.00 
ES A) a ee 1.56 
silver Chioride.......... 5. Se 
Dee VANIGE. © ix 2. 3.9 
SPN SELALE 6 sc5 Fs on 5 4. ee (19.°) 
PERS Seales Sis x har ia *. 2.05—2.7 
eripy (loose. 26.01... E26 
Sodium Picea tee sean. 1.4 
Bicarbonate... .. 2,10-2,22 
Pome OTOMICE s,s  kk: 2.95-3.08 
“< Carbonate 
famiiyd.,) 25. .2:43-2.51 
~~ Carbonate 
pet) oe 46 (17) 
Pe COMMIEMAG cy eisin wi 3 Pe Wis Gg 
ee eenrate tc... a71 {16.°) 
fo Dichrraate:..... 2.52 (16.°) 
pe BRAID OKI wuss: so. 21-3 
Seren NIG At eters. st 2.267 #2 
See Nite Pets ok 2k 7 
PE XI ee, 225805 
Ae Se kes nar 2.805 


oe. Phosphate 
NaeHPO.12H,O 1.5235 (16.°) 
Potassium Tar- 


fete eS ay 
- Sulphate (anhyd. E 671 4 
. 10H,O. .1.492 ce = 
iy Sulphide Nags... 2.471 
) sulpkite 7H.O: + .1- 561 
s a eides.  TA8 
eee Pabirate. 3.5. 1.794 
** Tetraborate 
foilreso a: F094)" 
«<  Thiosulphate 
iL) ie oe os, 1.729 (17.°) 
eee Pungstate... 6. .3.259 (47-5) 
Spatmculron Ore... 2... 3.7-3-9 
Stannous Chloride 2H,O. .2.71 (15.5°) 
aT elign wey fee. ees: 1,5371.50 
Stearic Acid. 2.2... 8428 % 
Seq rUriee eee os Gans .9245 (65. ) 
Sa WS, Seo ee 7.0-7.8 
strontium i ohiorate.... ...3.152 
Strontiam,Nitrate....., .2.24—2.98 


SUPATACANG) oc Gel oe i, oy eB pe 
Sulphur FEO Bren as ety, 
¥o>-amorph  solts a7 aes (0.°) 


Pe aplastic. :. ; 1.09 

< monoclinic SB... EE-O55 

ee TEGIN ECA ee 2.05-2.07 (0°) 
Sulphur Dioxid rece, © 2.2039 
Sulphuric Acid H,SQ,... . 1.8342 48 
bie TLCS Oe coats mn lt a 2.6-2.8 
Poles sepa eo eee 2.7 
Me ALtavicsAcid 3% -4o ttc. 1.666—-1.764 
Perpineolisaenas (ano ee. ck x 9357 (20.°) 
Thymol (3:2:1). . 0941 (0.°) 
Titanium Oxid TiO... Pn -3.75-4.25 
OWenel: seo eh a, OL aC 866 29 
TOWING, “A Ake eee .998-1.046 
Tungsten Oxid WO,: 

(OrOWh seas ee oe: 12.11 
Tungsten Oxid WO;: 

BvELLOW Ne et edge cor 7,16 
RA ans oe ee E393 
CuCl aes ts ee 8 dee ie 1.855-1.893 
WN CEGHOUIS ie te tt Simi esa 1.9 
Wax, Bees: 


Yellow m.p. 62.-62.5.°C .96-.965 


White m. p..63.—63.5°C. .96-.969 
Wax, Japan: 
(m. p. §3.5° 54-5"). + -992 
WV Tie Peete eh oa .7-.8 


Wood (see table on page 351). 
Wool (sheep) air-dry..... E32 


AM LCNG On aay 2 kee ee 8932 (c.°) 
Sees PEN aris eek ae 866 2% 
RRS a ewe Seen. kr ee 8801 (0.°) 
Zinc PCCLATE. Oe eG GY 
Blende ZnS. . .4.03-4.07 
ee Carbonate. sa. es shes 4.42-4.45 
en CRIOUe reader ae sete ae 
OE OSI Socio he ee cet 5-78 


‘* oup hate anya, ase 3.6235 (15.°) 
ig 7H20..... 1.964 
CA Reh a) uvin CoM Uncen et 3.98 


(All temperatures, unless otherwise noted, are given in Centigrade degrees.) 


CHEMISTRY AND TECHNOLOGY OF PAINTS 


SPECIFIC GRAVITY OF THE ELEMENTS 





400 
Alumni ae ee ne Se 
Anton yin te ee et 6.62 
Arcot: 8 astece 6 coe 1.379 (Air-I) 
ATSENIC. Whe peor ee cee 57.3 
Baran ee te tee 2075 
Bisnigtn ys: ea oe eee 9.80 
Boron Aaa teen ee ae 2.50 
Bromibes. > eee 3.15 (Air-I) 
Cadniium a) ee 8.64 
Caesitlin. ca fate ners 1.88 
Calcii 2. utero ote 

daP7 
Garbon. eee eee Gee 
Ceriimeag aestuarii 6.68 
Chiorne. a¥-7) see. 2.49 (Air-I) 
Chromitim.3 4 et 6.50 
Cobaltswieci.s ot be ae 8.60 
Columbium (Niobium). 7.20 
Coppers chem uctehiere 8.933 
Forbiuii ges ese ees ae: Wey 
Binerined, bee 1.26 (Air-I) 
Gadolinium. -.7-4)a cee mele 32 
Gallina {745-50 aera 5-95 
Germaniunis so.ae ee .469 
Glucinum (Beryllium).. 1.93 
Gold; acnee aS eee 19.32 
Hlelitimn Seen poe eee .1363 (Air—-I) 
Hydrorven: 52 a. ae .0696 (Air—-I) 
Tridiain Seas tar eee es yee 
Jodine wees ee 4.943 
eiditum . chee ce ee 22.42 
Tronts Gye Se oats 7.86 
Krypton 26-2 eee © 2.818 (Air-I) 
Lanthamtina 5: cia Os 46 
Téa ds 2 See Wick tae wa) ray 
Tathtum 5c sees cee 2 59 
Magnesiunisverce. aoe arter 4. 
Manganese. 5a) eee 7.39 
IM CRCUIY cheese are E355 
Molybdenum. +. ..%.., 8.60 
Neodymium wes) en 6.956 
Neon i408 os) see .674 (Air-I) 
Nickel ssgrg, Sinome see 8.90 











Nitrogen. ae 96737 
Osmium jc.2 2, pee 22.48 
Oxygen.) eee 1.10535(Air-I) 
Palladium... ee. ee II.40 
Phosphorus: 

(Whité)) 73 =aeeeee 1.83 

(Red)? 35 see 2.20 
Platinum 4a 21.50 
Potasstuny. to. 0 eee 87 
Praseodymium 6.4754 
Radium 4 ee 
Rhodium:<,.a ae sea 12.10 
Rubidium?<) ape Tis 
Rutheniums 7a eee 12.26 
Samarium eee foyer ae 
Scandium. < yee cee 
Selenium. 272 ees 4.8 
Silicon: 

(Cryst: 3 2 eee 2.39 

(Graphitic). eae 2.00 

(Amorph.) 2126 
Silver. 2. eee eee 10.50 
Sodiuni 3a eee .978 
Strontigm 3.2 eee oie4 
Sulphur 25 ose 2.07 
‘Tantalum <-> see 10.4 
Tellurium: 4 eee 6.25 
Tetrbium:<1 73) eee 
Thalltum: 5), eee 11.85 
Thorium: 2 = q9seeeee LT,.00 
Thubum,4.. eee 
Tit. 433420 eee 7:20 
Titanium (72. ieee 
Tungsten: 

(Wolframium)...... 19.1 ' 
Uranium see 18.7 
Vanadium. ee 50 
Xenon. >... see 4.422 (Air—I) 
Ytterbium .,.2 ee 
Yttrium... poe 3.80 
Zinc: .... 25 29. 7.25 
ZifCOniUn <4 6: eee 4.15 


PouNbDS OF OIL CONTAINED IN 100 POUNDS OF AVERAGE PASTES MADE FROM 
THE VARIOUS DRy PIGMENTS! 


Ashestine 06 iGicnsaa. ie one eee 32 
Barytes4 Natjto auto care 9 
Black BONG. - a eee aaa 50 
Black’ Dropsacgcteus eee 50 
Black, Hydro Gas Carbon....... 88 
Black, Lampws ok new eee ee 78 
Blapcukixexsc atecoser beens 25 


Blue, Chinese or Prussian........ 62 


Blue, Ultramannes eee eee 28 
Brown, Mineral.) 0) see 24 
Brown, Vandyke. 3.0 ee eee 58 
China Clay.5: 53h 28 
Dutch Pink (Quercitron Lake).... 28 
Graphite (Plumbago), 90%...... 48 
Green, Pure, Light, Chrome: .7. 7; 21 
Green, Pure, Dark; Catomenaae 28 


ANALYSIS OF PAINT MATERIALS 401 


Green, 25% Color, Light Chrome. 18 Sienna, Raw Italian............. 52 
meee or Watk Chrome:--20- Silex. oe ec le eee 24 
Green Earth (Terra Verte)....... G25) sumbers DurntcAmerican 21 ox. 36 
Green; fimerican, Paris... ........ Sa Mer, Rave PA INCTICAIA. fu. 5): 38 
Meee eieiish Paris... es. 5: Zong umber, burnt Purkeye tis... sue. 47 
fieen, Ultramarine... 2... ss Bienes Leber RA We EUPKEV ic 2 ys.o). lat. 48 
Re es Sb gs bes wiles 22 Vermilion, American (Chrome Rec) 18 
rinepnineis. 25. 85-50 oe go-25), » Vermilion; English (Mercury)...,. 14 
PIOMPOAATICTICAT) or. bw. oes 28 ~ White Lead (Basic Carbonate)..... 10 
PPGMGem EFCC): Ss wk ae es 28 White Lead (Basic Sulphate)..... 11 
Pearestazolden (Pure). 0. ..4... gore White, Panic (Whiting 22.0. 20 
Remerindian. (Pure o$:.%) <.. i..% -4 25-7 VelowsLemon, Chrome, wos... 128 
LeU OMU CSE 14 RS ae COverey cllow. Med). Ghrome.!. 2) 05 3s 30 
Poe ee CICUAN e545 oe ee ee 23 Yellow, Orange, Chrome......... 20 
meaeweon, Oxia \Pures 5.5.25... a5 Yellow, Dk. Orange; Chrome... . 18 
USSU ASS ae Ag POigeenyATCOLICHE a. pein tu ok eee Sg tk 12 
Digna, RaW AMIetICAnN .....°.... 45 Zinc Oxid (American), ordinary .. 18 
Siehna, Burnt [talian....4.. 5... Agee Linc. Oxid (White seals 25.0.0. bao 


1 These figures are approximately correct. For instance, lamp black is 
given as 78 pounds. There are, however, some lampblacks which require as much 
as 100 pounds, and others which require as low as 70 pounds, but 78 pounds is the 
exact amount for commercially pure lampblack. This figure means that roo 
pounds of lampblack will require 78 pounds (about to gallons) of oil to make 
a stiff paste. 


SpectrIC GRAVITY OF VARIOUS Woops 














Air dry Fresh 
LNG Ts Peete © ee ewer eee a50e 85 B75—100 
PACT Ma ner he Sas Ae 425-68 S62=- 17, O1 
0) 6) Ree Se ere SCO 04 Se La 
ASE RU aor on i a ge Ne a .57- .94 -7O-1:.. 04 
RE rechiey Sok ka oe ES te eh .80-1 .09 
[S05 EO ie tee ee ee .QI-1.16 | 1.20-1.26 
(etn Bn aeee a lye has, By ao eg Al Ce are 
Cherry hose eka .70— .84 | 1.05-1.18 
ULC eee ke Teed one nee ee 
Hod ELV ck oaarce ek ant AS atopy 7O-1.18 
Ae ape Ae Rin ig ee Marine Bera Su awn ia Nee 
Pa howan yo eek ae he B= TE OO ian tanh ee ati 
iA DIES Bek eee ciara pare, OF ROS-1505 
Mountain Ash. tee 69— .89 Seared 2 
[Da ora Re ees tens Snr hE 69-1 .03 93-1. 28 
Peni o® vets ear OF 75 Q6-I.07 
PANES rc: at ee oe ee 35— .60 40-1 .07 
Plameaxae eto toek oe .68-— .90 oy et ee Wy, 
PODIAL A eee chica o- 530-50 jOf=1 7107 
fF WILLOW asda tc eine te ot 49- .59 fie eae 





402 CHEMISTRY AND TECHNOLOGY OF PAINTS 


TABLE SHOWING THE COMPARISON OF THE READINGS OF THERMOMETERS 


Celsius, or Centigrade (C). Réaumur (R). Fahrenheit (F). 


























e er asa F C R F 

— 30 — 24.0 — 22.0 ae: 18.4 73.4 

— 25 — 20.0 — 13.0 24 19.2 7522 

— 20 — 16.0 — 4.0 25 20.0 TFL 

— 15 — 12.0 + 5.0 26 20.8 78.8 

— 10 — 8.0 Be © re: 27 21.6 80.6 

— 5 — 4.0 23.0 28 22.04 82.4 

— 4 — 3.2 24.8 20 23.52 84.2 

— 3 — 2.4 20.6 30 24.0 86.0 

— 2 — 1.6 28.4 31 24.8 87.8 

-— I — 0.8 40°22 32 25.6 89.6 

33 26.4 QI.4 

Freezing point of water. 34 S22 93.2 

35 28.0 95.0 

fo) 0.0 32.0 36 28.8 96.8 

I 0.8 33.8 ay 29.6 98.6 

2 1.6 35.6 38 30.4 100.4 

3 Phe’ carer 39 hae’. 102.2 

4 ano 20g 40 32.0 104.0 

G 4.0 ALLS 4I 328 105.8 

6 t 4.8 42.8 42 33.6 107.6 

7 5.6 44.6 43 34.4 109.4 

8 6.4 46.4 44 2059 iit 

9 yea) 48.2 45 36.0 E53 0 

10 8.0 50.0 50 40.0 T2220 

II 8.8 5r.8 55 44.0 131.0 

12 9.6 53.0 60 48.0 140.0 

13 10.4 re! 65 52.0 149.0 

14 to 2 Bias 70 56.0 158.0 

15 12.0 59.0 75 60.0 167.0 

16 12.8 60.8 80 64.0 176.0 

17 13,0 62.6 85 68.0 185.0 

18 14.4 64.4 go 72.0 194.0 

19 reg 66.2 05 76.0 203.0 

20 16.0 68.0 100 80.0 2120 

21 16.8 69.8 

22 17.6 wi 0 Boiling point of water. 














Readings on one scale can be changed into another by the following formule, 
in which /° indicates degrees of temperature: 


Réau. to Fahr. Cent. to Fahr. Fahr. to Cent. 
ZR 4n3e eB SC unsa mae 5( er-3°)-Pc 
4 5 9 

Réau. to Cent. Cent. to Réau. Fahr. to Réau. 





Se See Bagge Ce ‘(Pe P-32)-PR 
4 5 9 


BIBLIOGRAPHY 


Publications of great value to the paint manufacturer may be obtained 
from the various government departments. Address the Superintendent of 
Documents, Government Printing Office, Washington, D. C., for a list of titles 
of publications of interest to the paint color and varnish industry. The cost of 
most of these publications is five cents. 

Specifications, reports, etc., are also published by the Navy Department, 
Department of Agriculture, etc. 


PERIODICALS 


American Paint Journal, St. Louis. 
American Society for Testing Materials — Transactions. 
Chemical Abstracts. 
Chemische Zeitung, Ber.in. 
Chemical and Metallurgical Engineer, N. Y. 
Chemical Age, London. 
Chimie et Industrie, Paris. 
Drugs, Oils and Paints, Philadelphia. 
Farben Zeitung, Berlin. 
Journal of the American Chemical Society. 
Journal of the Franklin Institute, Philadelphia. 
Journal of the Chemical Society, London. 
Journal of the Society of Chemical Industry, London. 
Journal of Industrial and Engineering Chemistry. 
Journal of the Ou and Color Chemists Association, London. 
New Jersey Zinc Co., Bulletins, N. Y. 
Oil, Paint and Drug Reporter, New York. 
Oil and Colour Trades Journal, London. 
Paint Manufacturers Association, Bulletins, Washington. 
Paint, Ou and Chemical Review, Chicago. 
Paint and Varnish Society Papers, London, 
Paint and Varnish Record, New York. 
Revue de Chimie Industrielle, Paris. 
4093 


404 BIBLIOGRAPHY 


PAINT VARNISH AND COLORS 


ABRAHAM, H. Asphalts and Allied Substances. 

ANDES, Louris E. Iron Corrosion and Anti-fouling Paints. London, 
Scott, Greenwood & Son. 

Bearn, J. G. The Chemistry of Paints, Pigments and Varnishes. 
New York, D. Van Nostrand Co., 1924. 

BottLer, Max. Die Lack- und Firnisfabrication. Halle, Wilhelm 
Knapp, 1908. 

Cuurcu, A. H. The Chemistry of Paints and Paintings. London, 
Seeley Co., Ltd. 

DoERNER, Max. Mahlmaterial. Munich, 1922. 

Ertner, A. Uber Fette Ole. Munich, 1922. 

FRIEND, J. Newton. An Introduction to the Chemistry of Paints. 
London, Scott, Greenwood & Son, tgto. 

FRIEND, J. Newron. The Chemistry of Linseed Oil. London, 
Gurney & Jackson, 1917. 

Faurion, W. Die Chemie der Trockenden Ole, 1911. 

GARDNER, H. A. Physical and Chemical Testing of Paints, Varnishes 
and Cotors. Washington, 1925. 

GARDNER, H. A. Paint Researches and their Practical A pplication. 
Washington, Judd & Detweiler, 1917. 

GARDNER, H. A. Paint Technology and Tests. New York, McGraw- 
Hill =161 

HotiEy, C. D. Analysis of Paint and Varnish TIO: New 
York, J; Wiley, oro: 

Ho titey, C. D. Analysis of Paint Vehicles, Japans and Varnishes. 
New York, J. Wiley, 1920. 

Heaton, Nort & Hurst, C. H. Painters’ Colours, Owls and 
Varnishes. London, Charles Griffin & Co., 1922. 

Hurst, G. H. Dictionary of Raw Materials, Used in the Manufacture 
of Paints. London, Scott, Greenwood & Son, 1917. 

LewkowlrtscH, J. Oils, Fats and Waxes. New York, Macmillan Co. 

Moret, Ropert S. Varnishes and their Components. London, 
Oxford Technical Publications, 1923. 

PICKARD, GLENN H. Contributions to the American Paint Journal 
on paint and varnish materials; also to the Paint Man’s Pocket 
Library. St. Louis, American Paint Journal Co., 1922, ’23, ’24, 25. 

SaBiIn, A. H. The Industrial and Artistic Technology of Paint and 
Varnish. New York, J. Wiley, 1917. 


BIBLIOGRAPHY 40s 


SABIN, A. H. German and American Varnish M anufacture. New 
York, John Wiley & Sons. 

Scott, W. W. Standard Methods of Chemical Analysis, 1917. 

SEELIGMANN & ZickE. Handbuch der Lack-und Firnisindustrie. 
Berlin, 1923. 

SMITH, JAMES C. The Manufacture of Paint. London, Scott, Green- 
wood & Son, 1924. 

Tocu, M. How to Paint Permanent Pictures. Materials for Painting 
Permanent Pictures. 

TRUELOVE, Rupert H. Oils, Pigments, Paints, V arnishes, etc. 
London, Sir I. Pitman & Sons, Ltd., 1022. 

VAN Patten, Natuan. Bibliography of the Corrosion of Metals. 
Marblehead, 1923. 


PIGMENT COLORS 


Berscu, Joser. The M anufacture of Earth Colours. London, 
Scott, Greenwood & Son, 1921. 

BerscuH, Joser. The Manufacture of Mineral and Lake Colours. 
London, Scott, Greenwood & Son, root. 

GENTELE, J. Lehrbuch der Farbenfabrikation. Benue 
F. Vieweg & Sohn, 1909. 

JeNNIsON, Francis H. The Manufacture of Lake Pigments from 
Artificial Sources. London, Scott, Greenwood & Son, 1924. 

Lincke & Apam. Die Malerfarben. Esslingen, 1913. 

Metrrzinskt, S. Handbuch der Farben, Fabrikation, Praxis und 
Theorie. Vienna, A. Hartleben, 1808. 

Parry, J. and Coste, J. H. The Chemistry of Pigments. London, 

_ Scott, Greenwood & Son, 1902. 

Rrerautt, J. R. Colors for Painting (obsolete, but of Perey 
Binledelphia. hehe 

Rose, F. Die Mineralfarben. Leipzig, O. S. Spamer, 1916. 

Tocu, MaximiiAn. Materials for Permanent Painting (artistic). 
New York, D. Van Nostrand & Co., tort. 

ZERR & RUBENCAMP. A Treatise on Colour Manufacture. 

ZERR, GEORGE. Tests for Coal Tar Colours in Aniline Lakes. 


DYES, FORSLAKES 


Society of Dyers and Colourists, Colour Index. 1924. Manchester 
England. 


b 





INDEX 


i Balata, 285 
Barité Er 
Acetylene black, 106 Barium carbonate, 121 
Acid resin in paints, 153 analysis of, 359 
Adulteration with inert pigments, 108 chloride, 120 
Albalith, 40 peroxide, 120 
Alizarin, 143 sulphate, 110 
Alkali-proof green, 91-93 sulphide, 41, 119 
Aluminum hydrate, 140 Barnacles, 149 
Aluminum silicate, 127 Barytes, 110 
American tung oil, 218 analysis of, 359 
American turpentine, 251 Base, lake, 114 
American yellow ochre, 67 Basic lead sulphate. 32 
Ammonium oleate, 291 analysis of, 332 
Ammonium stearate, 291 . Battleship gray, 118 
Ammonium tannate, 291 Bottom salts, 31 
Anatase, 48 Becton white, 4o 
Angular blanc fixe, 121 Benzene, 273 
Anti-corrosive paint, 301 Benzine, 268 
Anti-fouling paints, 150 Benzol, 273 
Anti-rust — see corrosion Benzol black, 106 
Antimony oxid, 50 Bibliography, 403 
Antimony sulphide, 73 Bismuth, 114 
Antimony yellow, 73 Bitumen, 294 
Antwerp blue, 87 Black fungus, 324 
Arsenic sulphide, 74 Black lead, 99 
Arsenic yellow, 74 Black toner, 105 
Artificial calcium carbonate, 135 Black pigments, 95 
Artificial vermilion, 144 analysis of, 354 
Artists’ colors, 287 acetylene, 106 
Asbestine, 128 benzol, 106 
analysis of, 357 carbon, 98 
Asbestos, 128 charcoal, 102 
Aspergillus flavus, 324 coal, 104 
Aspergillus niger, 324 drop, 104 
Asphaltum paints, 155, 204 graphite, 99 
Atcheson graphite, too ivory, 104 
lamp, 96 
mineral, 107 
B sugar house, 95 
Baking japans — sec enamels vine, 103 
fish oil for, 230 Blanc fixe, 114 


407 


408 


Blanc fixe, analysis of, 355 
angular, 121 
Bleaching of linseed oil, 175 
China wood oil, 199 
Blown linseed oil, 187 
soya bean oil, 232 
Blue lead, 60 
Blue pigments, 82 
Antwerp, 87 
bronze, 87 
Chinese, 87 
cobalt, 85 
Guimet’s, 83 
milori, 87 
Paris, 87 
Prussian, 87 
analysis of, 351 
steel, 88 
ultramarine, 82 
analysis of, 352 
Bottoms, lead, 31 
Bronze blue, 87 
Brookite, 48 
Brown pigments, 75 
Brown, Vandyke, 80 
Burnt ochre, 78 
Burnt sienna, 75 
Burnt umber, 77 


C 


Cadmium lithopone, 73 
Cadmium orange, 73 
Cadmium yellow, 73 
Calcium carbonate, 130 


INDEX 


production in America, 218 
refining of crude, 199 . 
Chinese blue, 87 


Chinese wood oil — see China wood oil 


Chirt, 114 
Chromate of zinc, 71 
Chrome green, 90 
Chrome oxide green, or 
Chrome orange, 70 
analysis of, 348 
Chrome yellow, 70 
analysis of, 348 
Clay, 126 
analysis of, 357 
Coal, 104 
Cobalt blue, 85 
driers, 277 
linoleate, 281 
oleo resinate, 281 
resinate, 280 
salts, Inorganic, 277 
soap drier, 281 
Cod liver oil, 236 
Cod oil, 243 
Colophony, 250 
Combining mediums, 285 
Commercial whiting, 130 
Concrete as anti-corrosive, 313 
corrosion of steel in, 315 
paints for, 152 
Copper anti-fouling paints, 151 
Copperas, 65 
Copper carbonate, 93 
Corn oil, 247 


Calcium sulphate, 63 Corrosion of steel in concrete, 315 
analysis of, 356 Corrosion of structural steel, electro- 

Carbon black; 98 lytic, 311 

Cement as anti-corrosive, 313 Corrosion, protection against, 301 

Cement, paints containing, 155 Cream ochre, 68 


Cement, paints for, 152 

Chalk, 130 

Chalking of white lead, 29 

Charcoal, 102 

Charlton white, 40 

China wood oil, 191 
deodorization, 222 
examination of, 203 
heat and quality tests, 211 


Creosote in shingle stains, 161 
Cresol, 161 


D 


Damar in enamels, 156, 188 
Damp-resisting paints, 155 
Darkening of pigments, 297 
Deodorization of tung oil, 222 
Diatoms, 126 


Diazotization, 141 
Dispersion, 391 

Drop black, 104 

Drying of linseed oil, 168 
Durability of paints, 146 
Durex white, 121 

Dutch Boy red lead, 55 
Dutch process white lead, 26 


E 


Emerald oxid green, 93 
FEmulsifier, pine oil as, 290 
Emulsifiers, 287 

Enamel oil, 184, 186, 187 
Enamels, 156 

Erythrosine, 289 
Examination of China wood oil, 203 
Examination of pigments, 326 
Exfoliating paints, 150 
Extenders, 108 

Extra gilder’s whiting, 130 


F 


Fading of pigments, 297 
Ferric oxids, 62 
analysis of, 344 
Ferrite, 72 
Ferrox, 72 
Fibre, asbestos, 127 
Fillers in white lead, 30 
Fine grinding, 292 
Fish oil, 236 
treatment of, 238 
Flat paints, 121, 160 
Floor paints, 161 
Florence zinc, 23, 38 
Franklinite, 36 
French ochre, 67 
French turpentine, 251 
French zinc, 38 
Fuller’s earth, 126, 127 
Fungicides, 325 
Fungi on paint, 322 


G 


Galena, 22-60 
Golden antimony, 73 


INDEX 


Golden ochre, 68 
Graphite, 99 
analysis of, 355 
Gray, battleship, 118 
Gray ochre, 68 
Green fungus, 324 
Green ochre, 69 
Green pigments, go 
alkali-proof, 91-93 
chrome, 90 
chrome oxid, ot 
copper, 93 
hydrated chrome oxid, 93 
Veronese, 93 
Crrcen cal. 23,038 
Grinding, 8, 290 
Growth of fungi on paint, 322 
Gum chicle, 285 
Gutta percha, 155, 285 
Gypsum, 135 


ie! 


Herring oil, 243 

Hydrogen sulphide, action on lead, 30 
action on zinc, 36 : 

Hygiene, painter’s, 319 

Hypernic lake, 144 


Tlmenite, 48 
Imitation vermilion, 144 
Indian red, 64 
Inert fillers, 108 
Inert fillers in white lead, 30 
Infusorial earth, 122, 126 
Tron oxids, red, 62 

analysis of, 344 
Iron oxids, yellow, 72 
Ivory black, 104 


it 


Japanners’ brown, 169, 186 
Japanners’ brown oil, 186 
Jersey Lily White, 40 


409 


4IO 

K 
Kaolin, 127 
Kieselguhr, 126 
King’s yellow, 74 

ib; 


Lake base, 114 
Lakes, 140 
Lampblack, 96 
Lapis lazuli, 82 
Lead, black, 99 
Lead carbonate, 27 
oxids, 52 
poisoning, 27, 319 
sulphate, 31 
white, 25 
Leaded zinc, 24 
Leather, fish oil for, 239 
Light-proof lithopone, 44 
Limeproof colors, 144 
Linseed oil, 164 
bleaching of, 175 
boiled, 187 
drying of, 168 
porosity of, 172 
specifications for, 180 
Liquid mills, 8 
Litharge, 52 
Tithol red, 143 
Lithopone, 40 
analysis of, 338 
light-proof, 44, 47» 
zinc oxid in, 47 
Lumbang oil, 223 


M 


Madder lake, 143 

Magnesium silicate, 128 

Maize oil, 247 

Marble dust, 134 

Maroon lakes, 145 

Mass tone of colors — see shade 
Measure, tables of, 394 

Menhaden oil, 237 

Mercury in anti-fouling paints, 151 





INDEX 


Mercury, vermilion, 141 
analysis of, 347 
Metric — English conversion tables, 394 


_ Mills, 6 


liquid, 8 

paint, 8 

pebble, 19 

roller, 22 
Milori blue, 87 
Mineral black, 107 
Mineral Point zinc, 23, 88 
Mixed paints, 1, 6, 146 

analysis of, 362, 360 
Mixers, 6 


N 


Navy, U.S. — use‘of blanc fixe, 11 
New Jersey zinc, 23, 38 


O 


Ochre, 67 

Oil soluble colors, 145 

Oils, analysis of, 379 
American tung, 218 
boiled linseed, 187 
China wood, tor 
cod liver, 236, 243 
com, 247 
enamel, 184, 186, 187 
fish, 236 
herring, 243 
japanners’ brown, 186 
linseed, 164 
linseed, boiled, 187 
maize, 247 
menhaden, 237 
perilla, 188 
pine, 258 

_ porpoise, 236, 243 
sardine, 242 
seal, 2209243 
soya bean, 225 
stand, 184, 187 
stillingia, 224 
tung, 191 
whale, 236, 243 
winter pressed, 244 


INDEX 


Oleum white, 40 
Orange, chrome, 70 
analysis of, 348 
Orange mineral, 53 
analysis of, 343 

Orpiment, 74 
Orr’s white, 40 
Oxids of lead, 52 
Ozark white, 34 


i 


Paint, analysis of mixed, 362, 369 
anti-corrosive — see corrosion 
anti-fouling, 150 
containing Portland cement, 155 
damp-resisting, 155 
determination of water_in, 377 
enamel, 156 
flat wall, 160 
floor, 161 
‘for cement and concrete, 152 
mills, 8 
mixed, 1, 6, 146 
mixed, analysis of, 362, 369 
poisoning by, 319 
shingle, 161 
to prevent corrosion, 301 
waterproof, 155 

Painter’s hygiene, 319 

Paper coating, 114 

Paranitraniline, 141 

Para red, 141 

Para rubber, 285 

Para toner, 141 

Paris blue, 87 

Paris white, 130 

Paste figures for pigments, 400 

Pebble mills, 19 

Pencillium Arustaceum, 324 

Perilla oil, 188 

Permanent white, 114 

Peroxide of barium, 120 

Pigments, amounts of, required for 

paste, 409 
fading and darkening of, 297 
standards, 326 
testing and examination, 326 


AII 


Pine oil, 258 
Poisoning lead, 27, 319 
Poisonous anti-fouling paints, 151 
Poisonous paints for fungi, 322 
Ponolith, 40 
Porosity of linseed oil films, 172 
Porpoise oil, 236, 243 
Portland cement — see cement 
Prince’s metallic brown, 79 
Production of tung oil in America, 218 
Protection against corrosion, 301 
Prussian blue, 87 

analysis of, 351 
Eutty, £32 


Quartz, 123 


Raw sienna, 70 
Raw umber, 77 
Realgar, 74 
Red, Indian, 64 
Red lakes, 144 
Red lead, 53 
Red oxides, 62 

analysis of, 344 
Red Seal zinc, 23-38 
Red, Venetian, 63 
Refining of China wood oil, 199 
Refractive index, 389 
Refractometer, Abbé, 3389 
Refractometry, 389 
Reinforcing pigments, 108 
Reinforcing reds, corrosion of, 315 
Resinate of cobalt, 280 
Rhizopus Nigricans, 324 
Roller mills, 22 
Rosin, 250 

determination of, 371 
Rosin oil, detection of, 375 
Rouge, 66 
Rub-outs, 327 
Rusting — see corrosion 
Rutile, 48 


S 
Salt water, influence on paint, 117, 119 
Sardine oil, 242 
Scarlet lake, 144 


A412 


Sea coast painting, 32, 240 
Seal oil, 236, 243 
Sea water, influence on paint, 117-119 
Shade of pigments, 327 
Shingle paint, 161 ~ 
Shingle stain, 161 
Ship’s bottom paints, 150 
Sienna, raw, 70 
analysis of, 345 
Suex, ores 
Silicas-1 22 
analysis of, 357 
Silicate of alumina, 127 
Silicate of magnesia, 128 
Smokestack paints, 239 
Sodium sulphate, 120 
Sodium sulphide, 120 
Soluble in oil, colors, 145 
Solvent naphtha, 276 
Soya bean oil, 225 
blowing and drying of, 232 
physical constants of, 231 
Spanish white, 135 
Specifications for linseed oil, 180 
Specific gravity of elements, 400 
Specific gravity of misc. materials, 396 
Specific gravity of various woods, 4o1 
Spirit, white, 272 
Stains, shingle, 161 
Stand oil, 184, 187 
Steel blue, 88 
Steel, corresion of, 301 
electrolytic corrosion of, 311 
Stillingia oil, 224 
Stove polish, 99 
Structural steel, electrolytic corrosion 
of, 311 
Sublimed white lead, 31 
Substitute turpentine, 273 
Sugar house black, 95 
Sulphate of barium, 120 
Sulphate of calcium, 63 
Sulphate of lead, 31 
Sulphate of zinc, 39-40 
Sulphide of barium, 41, 120 
Sulphide of sodium, 120 
Sunlight — influence on paints, 294 
on pigments, 297 


INDEX 


A 
Tables: 
atomic weights, inside front cover 
dry pigments in oil, amount required 
for paste, 400 
metric-English conversion, 394-395 
specific gravity of elements, 400 
specific gravity of misc. materials, 396 
specific gravity of various woods, 4o1 
thermometer conversion, 402 
weights and measures, 394-395 
Testing of pigmemts, 326 __ 
Thermometer conversion formulas, 402 
Timonox, 50 
Titanium white, 48 
analysis of, 340 
Titanox, 48 
Tockolith, 155 
Toluidine toners, 142 
Toluol, 275 
Toners, 140 
Tooth, 114, 124 
Tungates, 234 
Tung oil — sce China wood oil 
Turpentine, 250 
American, 251 
French, 251 
Russian, 251 
substitute, 273 
wood, 251, 255 
Tuscan red, 144 


U 
Ultramarine, 82 
analysis of, 352 
Umber, 77 
analysis of, 345 


V 

Vandyke brown, 80 
Venetian red, 63 
Vermilion, artificial, 144 
Vermilion, mercury, 141 

analysis of, 347 
Veronese green, 93 
Verte antique, 93 
Vine black, 103 
Viridian, 93 


INDEX 


W 


Watch-case rouge, 66 
Water in paints, 286 
detection of, 289, 377 
Waterproof paints, 155 
Weights, tables of, 394 
Whale oil, 236, 243 
White lead, 25 
analysis of, 330 
bottoms, 31 
chalking, 29 
crystals in, 29 
oil absorbtion, 28 
sublimed, 24, 32 
White mineral primer, 134 
White mixed paints, analysis of, 362 
White, Paris, 130 
White pigments, comparative merits 
of, 24 
mixtures of, 24 
White, Spanish, 130 
White spirit, 272 
Whiting, 130 
Wood turpentine, 251-255 


Xylol,-276 


yi 
Yellow, chrome, 70 
analysis of, 347 
Yellow iron oxide, 72 
Yellow ochre, 69 


Zinc chromate, 71 
Zinc, leaded, 24 
analysis of, 333 
Zinc oxid, 36 
analysis of, 335 
Florence. 23, 45 
Green Seal, 23, 38 
in lithopone, 47 
Mineral Point, 23, 38 
Red Seal, 23, 38 
Zinc sulphate, 39, 40 
Zinc, yellow, 71 
Zincite, 36 
Zinox, 40 


413 


D. VAN NOSTRAND COMPANY 


are prepared to supply, either from 
their complete stock or at 


short nottee. 


Any Technical or 
Scientific Book 


In addition to publishing a very large 
and varied number of SCIENTIFIC AND 
ENGINEERING Booxs, D. Van Nostrand 
Company have on hand the largest 
assortment in the United States of such 
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fully answered and compiete catalogs 


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